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The ordinal (also 2nd), being the element of an ordered set preceded by just one other, and indirectly from that, the element of a second layer of subdividing. In a hierarchical scheme of subdivided units, the unit of the second rung or layer. Often a subdivision of minute, and then rarely other than a sixtieth of a minute, but also a subdivision of prime, when it is often a tenth. Being the second subdivision, it is commonly represented by a double prime mark, e.g. 3″ for 3 seconds of time, of angle, etc.

length British Using the symbol ″ but not its name, a denotation for inch, the second subdivision (following foot) of yard. Also as link, = ¹/₁₀ prime= ¹/₁₀₀ Rathborn chain = ⁹⁹/₅₀ in = 1.98 in (50.292 mm).

time. Symbol s in the SI. Traditionally ¹/₆₀ of a minute, thereby ¹/₈₆₄₀₀ of a day (a unit varying in size depending on the qualifier) and sized by such fractioning. Since 1967, however, the second of normal usage (derived from the mean solar day), the base unit for time in the SI and other metric systems, has been defined as the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom.
[Bergquist J. C., Jefferts S. R., Wineland D. J. Phys. Today Vol. 54:3, 37-44 (2000) on-line at http://physicstoday.org/pt/vol-54/iss-3/p37.html] It has since been affirmed that this applies to a caesium atom at rest at 0 K, so unperturbed by black-body radiation, hence that the frequencies of primary frequency standards should be corrected for ambient radiation.The scale on second of time in any definition is:

geometry (also arcsec, second of arc) Also as sec and often as the symbol ″, the second layer of fractioning (after minute) of the degree, the traditional measure of plane angle; = ¹/₆₀ min = ^1°/₃₆₀₀ =

astronomy Note: for right ascension the second of the sidereal clock, for declination, etc., it is the second of plane angle, a ratio of 15:1.

music (2nd) See interval.

other For second degree, see degree.

see also centesimal second; Redwood; Saybolt Universal Second.

noun

A very brief time: crack, flash, instant, minute¹, moment, trice, twinkle, twinkling, wink. Informal jiff, jiffy. Chiefly British tick. See big/small/amount, time.

noun

A person who holds a position auxiliary to another and assumes some of the superior's responsibilities: adjutant, aide, assistant, auxiliary, coadjutant, coadjutor, deputy, helper, lieutenant. See help/harm/harmless.

Idioms beginning with second:
second hand
second thoughts
second fiddle
second best
second childhood
second cousin
second nature
second sight
second to none
second wind

See also at second hand; come off (second best); in a flash (second); in the first (second) place; on second thought; play second fiddle; split second; top (second) banana.

Definition: subordinate
Antonyms: first, top

v

Definition: support, advance a suggestion
Antonyms: move

ˈsekǝnd ordinal number 1. constituting number two in a sequence; coming after the first in time or order; 2nd.

2. denoting someone or something regarded as comparable to or reminiscent of a better-known predecessor: a fear that the conflict would turn into a second Vietnam.

3. an act or instance of seconding.

2. subordinate or inferior in position, rank, or importance: it was second only to Copenhagen among Baltic ports

3. an attendant assisting a combatant in a duel.

formally support or endorse (a nomination or resolution or its proposer) as a necessary preliminary to adoption or further discussion: He seconded the nomination.

See the Introduction, Abbreviations and Pronunciation for further details.

The INTERVAL between any adjacent diatonic scale degrees (e.g. C-D, E♭-F). If the interval is a whole tone it is a major 2nd, if a semitone, a minor 2nd.

1. Base unit of time in the SI system; symbol s. It was formerly defined as 1/86 400 of the mean solar day, but it is now defined in terms of periods of radiation from a caesium-133 atom.

2. A unit of angle equal to 1/60 of a minute of an arc.

To convert from seconds (angle) to:

degrees, multiply by 2.7777778E-04.
minutes, multiply by .01666667.
quadrants, multiply by 3.087E-06.
radians, multiply by 4.848137E-06.

The interval of two diatonic degrees.

1. symbol: s; the SI base unit of time, equal to the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom.
2. symbol: ″ a unit of plane angle equal to 1/60 of a minute; i.e. 4.84814 microradian (π/648000 rad). See angle (def. 1).

The SI unit of time. Symbol s. Abbreviated sec.

• Maps and Cartography - second: one-sixtieth of one minute of one degree of latitude or longitude
• Principles of Mechanics, Waves, and Measurement - second: fundamental SI unit of time measurement, equivalent to 9,192,631,770 emission cycles of cesium-133
• Measures and Standards of Time - second: unit of time equal to 160 of a minute
• U.S. System - second: unit of angular measure equal to 1/60 of a minute or 1/3600 of a degree
• Acts, Powers, Conditions, and Procedures - second: (vb) endorse another’s parliamentary motion
• Harmony, Melody, and Structure - second: tone on the next degree from a given tone; interval between such tones
• Boxing and Wrestling
• Periods of Time - second: one sixtieth of a minute; fundamental unit of time equal to 9,192,631,770 emission cycles of cesium-133
• Support, Encouragement, and Agreement - second: (vb) give support or encouragement; endorse a motion

This article is about the unit of time. For other uses, see Second (disambiguation).

A light flashing approximately once per second

The second (SI unit symbol: s) is the International System of Units (SI) base unit of time^[1] and also a unit of time in other systems (abbreviated s or sec^[2]). Between 1000 (when al-Biruni used seconds) and 1960 the second was defined as 1/86,400 of a mean solar day (that definition still applies in some astronomical and legal contexts).^[3][4] Between 1960 and 1967, it was defined in terms of the period of the Earth's orbit around the Sun in 1900,^[5] but it is now defined more precisely in atomic terms. Seconds may be measured using mechanical, electric or atomic clocks.

However, 19th- and 20th-century astronomical observations revealed that this average time is lengthening and thus the sun–earth motion is no longer considered a suitable basis for definition. With the advent of atomic clocks, it became feasible to define the second based on fundamental properties of nature. Since 1967, the second has been defined to be:

the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom.^[1]

SI prefixes are frequently combined with the word second to denote subdivisions of the second, e.g., the millisecond (one thousandth of a second), the microsecond (one millionth of a second), and the nanosecond (one billionth of a second). Though SI prefixes may also be used to form multiples of the second such as kilosecond (one thousand seconds), such units are rarely used in practice. The more common larger non-SI units of time are not formed by powers of ten; instead, the second is multiplied by 60 to form a minute, which is multiplied by 60 to form an hour, which is multiplied by 24 to form a day.

The second is also the base unit of time in the centimetre-gram-second, metre-kilogram-second, metre-tonne-second, and foot-pound-second systems of units.

Contents 1 International second 2 Equivalence to other units of time 3 History 3.1 Before mechanical clocks 3.2 Seconds measured by mechanical clocks 3.3 Modern measurements 4 SI multiples 5 Other current definitions 6 See also 7 References 8 External links

International second

Under the International System of Units (via the International Committee for Weights and Measures, or CIPM), since 1967 the second has been defined as the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom.^[1] In 1997 CIPM added that the periods would be defined for a caesium atom at rest, and approaching the theoretical temperature of absolute zero, and in 1999, it included corrections from ambient radiation.^[1]

This definition refers to a caesium atom at rest at a temperature of 0 K (absolute zero). Absolute zero implies no movement, and therefore zero external radiation effects (i.e., zero local electric and magnetic fields). The second thus defined is consistent with the ephemeris second, which was based on astronomical measurements. (See History below.)

The realization of the standard second is described briefly in a special publication from the National Institute of Standards and Technology,^[6] and in detail by the National Research Council of Canada.^[7]

Equivalence to other units of time

1 international second is equal to:

• 1/60 minute (but see also leap second)
• 1/3,600 hour
• 1/86,400 day (IAU system of units)
• 1/31,557,600 Julian year (IAU system of units)

History

Before mechanical clocks

The Egyptians subdivided daytime and nighttime into twelve hours each since at least 2000 BC, hence the seasonal variation of their hours. The Hellenistic astronomers Hipparchus (c. 150 BC) and Ptolemy (c. AD 150) subdivided the day sexagesimally and also used a mean hour (¹⁄₂₄ day), simple fractions of an hour (¹⁄₄, ²⁄₃, etc.) and time-degrees (¹⁄₃₆₀ day or four modern minutes), but not modern minutes or seconds.^[8]

The day was subdivided sexagesimally, that is by ¹⁄₆₀, by ¹⁄₆₀ of that, by ¹⁄₆₀ of that, etc., to at least six places after the sexagesimal point (a precision of better than 2 microseconds) by the Babylonians after 300 BC. For example, six fractional sexagesimal places of a day was used in their specification of the length of the year, although they were unable to measure such a small fraction of a day in real time. As another example, they specified that the mean synodic month was 29;31,50,8,20 days (four fractional sexagesimal positions), which was repeated by Hipparchus and Ptolemy sexagesimally, and is currently the mean synodic month of the Hebrew calendar, though restated as 29 days 12 hours 793 halakim (where 1 hour = 1080 halakim).^[9] The Babylonians did not use the hour, but did use a double-hour lasting 120 modern minutes, a time-degree lasting four modern minutes, and a barleycorn lasting 3¹⁄₃ modern seconds (the helek of the modern Hebrew calendar),^[10] but did not sexagesimally subdivide these smaller units of time. No sexagesimal unit of the day was ever used as an independent unit of time.

In 1000, the Persian scholar al-Biruni gave the times of the new moons of specific weeks as a number of days, hours, minutes, seconds, thirds, and fourths after noon Sunday.^[4] In 1267, the medieval scientist Roger Bacon stated the times of full moons as a number of hours, minutes, seconds, thirds, and fourths (horae, minuta, secunda, tertia, and quarta) after noon on specified calendar dates.^[11] Although a third for ¹⁄₆₀ of a second remains in some languages, for example Polish (tercja) and Turkish (salise), the modern second is subdivided decimally.

Seconds measured by mechanical clocks

The earliest clocks to display seconds appeared during the last half of the 16th century. The earliest spring-driven timepiece with a second hand which marked seconds is an unsigned clock depicting Orpheus in the Fremersdorf collection, dated between 1560 and 1570.^{[12]:417–418[13]} During the 3rd quarter of the 16th century, Taqi al-Din built a clock with marks every 1/5 minute.^[14] In 1579, Jost Bürgi built a clock for William of Hesse that marked seconds.^[12]:105 In 1581, Tycho Brahe redesigned clocks that displayed minutes at his observatory so they also displayed seconds. However, they were not yet accurate enough for seconds. In 1587, Tycho complained that his four clocks disagreed by plus or minus four seconds.^[12]:104

The second first became accurately measurable with the development of pendulum clocks keeping mean time (as opposed to the apparent time displayed by sundials). In 1644, Marin Mersenne calculated that a pendulum with a length of 39.1 inches (0.994 m) would have a period at standard gravity of precisely two seconds, one second for a swing forward and one second for the return swing, enabling such a pendulum to tick in precise seconds.

In 1670, London clockmaker William Clement added this seconds pendulum to the original pendulum clock of Christian Huygens.^[15] From 1670 to 1680, Clement made many improvements to his clock and introduced the longcase or grandfather clock to the public. This clock used an anchor escapement mechanism with a seconds pendulum to display seconds in a small subdial. This mechanism required less power, caused less friction and was accurate enough to measure seconds reliably as one-sixtieth of a minute than the older verge escapement. Within a few years, most British precision clockmakers were producing longcase clocks and other clockmakers soon followed. Thus the second could now be reliably measured.

Modern measurements

In 1956 the second was defined in terms of the period of revolution of the Earth around the Sun for a particular epoch, because by then it had become recognized that the Earth's rotation on its own axis was not sufficiently uniform as a standard of time. The Earth's motion was described in Newcomb's Tables of the Sun (1895), which provide a formula estimating the motion of the Sun relative to the epoch 1900 based on astronomical observations made between 1750 and 1892.^[5] The second thus defined is

the fraction 1/31,556,925.9747 of the tropical year for 1900 January 0 at 12 hours ephemeris time.^[5]

This definition was ratified by the Eleventh General Conference on Weights and Measures in 1960. The tropical year in the definition was not measured, but calculated from a formula describing a mean tropical year that decreased linearly over time, hence the curious reference to a specific instantaneous tropical year. This definition of the second was in conformity with the ephemeris time scale adopted by the IAU in 1952,^[16] defined as the measure of time that brings the observed positions of the celestial bodies into accord with the Newtonian dynamical theories of their motion (those accepted for use during most of the 20th century being Newcomb's Tables of the Sun, used from 1900 through 1983, and Brown's Tables of the Moon, used from 1923 through 1983).^[5]

With the development of the atomic clock, it was decided to use atomic clocks as the basis of the definition of the second, rather than the revolution of the Earth around the Sun.

Following several years of work, Louis Essen from the National Physical Laboratory (Teddington, England) and William Markowitz from the United States Naval Observatory (USNO) determined the relationship between the hyperfine transition frequency of the caesium atom and the ephemeris second.^[5][17] Using a common-view measurement method based on the received signals from radio station WWV,^[18] they determined the orbital motion of the Moon about the Earth, from which the apparent motion of the Sun could be inferred, in terms of time as measured by an atomic clock. They found that the second of ephemeris time (ET) had the duration of 9,192,631,770 ± 20 cycles of the chosen caesium frequency.^[17] As a result, in 1967 the Thirteenth General Conference on Weights and Measures defined the second of atomic time in the International System of Units as

FOCS 1, a continuous cold caesium fountain atomic clock in Switzerland, started operating in 2004 at an uncertainty of one second in 30 million years.

the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom.^[5]

This SI second, referred to atomic time, was later verified to be in agreement, within 1 part in 10¹⁰, with the second of ephemeris time as determined from lunar observations.^[19] (Nevertheless, this SI second was already, when adopted, a little shorter than the then-current value of the second of mean solar time.^[20][21])

During the 1970s it was realized that gravitational time dilation caused the second produced by each atomic clock to differ depending on its altitude. A uniform second was produced by correcting the output of each atomic clock to mean sea level (the rotating geoid), lengthening the second by about 1×10⁻¹⁰. This correction was applied at the beginning of 1977 and formalized in 1980. In relativistic terms, the SI second is defined as the proper time on the rotating geoid.^[22]

The definition of the second was later refined at the 1997 meeting of the BIPM to include the statement

This definition refers to a caesium atom at rest at a temperature of 0 K.

The revised definition seems to imply that the ideal atomic clock contains a single caesium atom at rest emitting a single frequency. In practice, however, the definition means that high-precision realizations of the second should compensate for the effects of the ambient temperature (black-body radiation) within which atomic clocks operate, and extrapolate accordingly to the value of the second at a temperature of absolute zero.

Today, the atomic clock operating in the microwave region is challenged by atomic clocks operating in the optical region. To quote Ludlow et al.,^[23] “In recent years, optical atomic clocks have become increasingly competitive in performance with their microwave counterparts. The overall accuracy of single trapped ion based optical standards closely approaches that of the state-of-the-art caesium fountain standards. Large ensembles of ultracold alkaline earth atoms have provided impressive clock stability for short averaging times, surpassing that of single-ion based systems. So far, interrogation of neutral atom based optical standards has been carried out primarily in free space, unavoidably including atomic motional effects that typically limit the overall system accuracy. An alternative approach is to explore the ultranarrow optical transitions of atoms held in an optical lattice. The atoms are tightly localized so that Doppler and photon-recoil related effects on the transition frequency are eliminated.”

The NRC attaches a "relative uncertainty" of 2.5×10⁻¹¹ (limited by day-to-day and device-to-device reproducibility) to their atomic clock based upon the ¹²⁷I₂ molecule, and is advocating use of an ⁸⁸Sr ion trap instead (relative uncertainty due to linewidth of 2.2×10⁻¹⁵). See magneto-optical trap and "Trapped ion optical frequency standards". National Physical Laboratory. http://www.npl.co.uk/server.php?show=ConWebDoc.1086.  Such uncertainties rival that of the NIST F-1 caesium atomic clock in the microwave region, estimated as a few parts in 10¹⁶ averaged over a day.^[24][25]

SI multiples

SI prefixes are commonly used to measure time less than a second, but rarely for multiples of a second (which is known as metric time). Instead, the non-SI units minutes, hours, days, Julian years, Julian centuries, and Julian millennia are used.

SI multiples for second (s)

Submultiples				Multiples
Value	Symbol	Name		Value	Symbol	Name
10−1 s	ds	decisecond		101 s	das	decasecond
10−2 s	cs	centisecond		102 s	hs	hectosecond
10−3 s	ms	millisecond		103 s	ks	kilosecond
10−6 s	µs	microsecond		106 s	Ms	megasecond
10−9 s	ns	nanosecond		109 s	Gs	gigasecond
10−12 s	ps	picosecond		1012 s	Ts	terasecond
10−15 s	fs	femtosecond		1015 s	Ps	petasecond
10−18 s	as	attosecond		1018 s	Es	exasecond
10−21 s	zs	zeptosecond		1021 s	Zs	zettasecond
10−24 s	ys	yoctosecond		1024 s	Ys	yottasecond
Common prefixes are in bold

Other current definitions

For specialized purposes, a second may be used as a unit of time in time scales where the precise length differs slightly from the SI definition. One such time scale is UT1, a form of universal time. McCarthy and Seidelmann refrain from stating that the SI second is the legal standard for timekeeping throughout the world, saying only that "over the years UTC [which ticks SI seconds] has become either the basis for legal time of many countries, or accepted as the de facto basis for standard civil time".^[26]

See also

• Atomic clock
• Becquerel
• Coordinated Universal Time
• Hertz
• International Atomic Time
• International System of Units
• Leap second
• Magneto-optical trap
• Time standard

References

1. ^ ^{a b c d} "Official BIPM definition". BIPM. http://www.bipm.org/en/si/si_brochure/chapter2/2-1/second.html. Retrieved 2012-03-24. 
2. ^ [1 sec], Merriam Webster Learner's Dictionary, http://www.learnersdictionary.com/search/sec[1], retrieved 2012-03-24 
3. ^ International System of Units from NIST accessed 25 March 2012.
4. ^ ^{a b} al-Biruni (1879). The chronology of ancient nations: an English version of the Arabic text of the Athâr-ul-Bâkiya of Albîrûnî, or "Vestiges of the Past". Sachau C Edward. pp. 147–149. http://books.google.com/?id=pFIEAAAAIAAJ&pg=PA148#v=onepage&q=. 
5. ^ ^{a b c d e f} "Leap Seconds". Time Service Department, United States Naval Observatory. http://tycho.usno.navy.mil/leapsec.html. Retrieved 2012-03-24. 
6. ^ BN Taylor, A Thompson (Eds.), ed. (2008). "Appendix 2". The International System of Units (SI). NIST Special Publication. 330. pp. 53 ff. http://physics.nist.gov/Pubs/SP330/sp330.pdf. Retrieved 2009-08-19. 
7. ^ "NRC's Cesium Fountain Clock - FCs1". National Research Council of Canada. http://www.nrc-cnrc.gc.ca/eng/projects/inms/fountain-clock.html. Retrieved 2009-08-19. 
8. ^ Toomer, G. J. (1998). Ptolemey's Almagest. Princeton, New Jersey: Princeton University Press. pp. 6–7, 23, 211–216. ISBN 978-0-691-00260-6. 
9. ^ O Neugebauer (1975). A history of ancient mathematical astronomy. Springer-Verlag. ISBN 0-387-06995-X. 
10. ^ See page 325 in O Neugebauer (1949). "The astronomy of Maimonides and its sources". Hebrew Union College Annual 22: 321–360. 
11. ^ R Bacon (2000) [1928]. The Opus Majus of Roger Bacon. BR Belle. University of Pennsylvania Press. table facing page 231. ISBN 978-1-85506-856-8. 
12. ^ ^{a b c} Landes, David S. (1983). Revolution in Time. Cambridge, Massachusetts: Harvard University Press. ISBN 0-674-76802-7. 
13. ^ Willsberger, Johann (1975). Clocks & watches. New York: Dial Press. ISBN 0-8037-4475-7.  full page color photo: 4th caption page, 3rd photo thereafter (neither pages nor photos are numbered).
14. ^ Taqi al-Din
15. ^ Jessica Chappell (Oct 1, 2001). "The Long Case Clock: The Science and Engineering that Goes Into a Grandfather Clock". Illumin 1 (0): 1. http://illumin.usc.edu/184/the-long-case-clock-engineering-behind-a-grandfather-clock/. 
16. ^ Explanatory Supplement to the Astronomical Ephemeris and the American Ephemeris and Nautical Almanac (prepared jointly by the Nautical Almanac Offices of the United Kingdom and the United States of America, HMSO, London, 1961), at Sect. 1C, p.9), stating that at a conference "in March 1950 to discuss the fundamental constants of astronomy ... the recommendations with the most far-reaching consequences were those that defined ephemeris time and brought the lunar ephemeris into accordance with the solar ephemeris in terms of ephemeris time. These recommendations were addressed to the International Astronomical Union and were formally adopted by Commission 4 and the General Assembly of the Union in Rome in September 1952."
17. ^ ^{a b} W Markowitz, RG Hall, L Essen, JVL Parry (1958). "Frequency of cesium in terms of ephemeris time". Physical Review Letters 1 (3): 105–107. Bibcode 1958PhRvL...1..105M. doi:10.1103/PhysRevLett.1.105. http://www.leapsecond.com/history/1958-PhysRev-v1-n3-Markowitz-Hall-Essen-Parry.pdf. 
18. ^ S Leschiutta (2005). "The definition of the 'atomic' second". Metrologia 42 (3): S10–S19. Bibcode 2005Metro..42S..10L. doi:10.1088/0026-1394/42/3/S03. 
19. ^ W Markowitz (1988). AK Babcock, GA Wilkins. ed. The Earth's Rotation and Reference Frames for Geodesy and Geophysics. IAU Sumposia #128. pp. 413–418. Bibcode 1988IAUS..128..413M. 
20. ^ DD McCarthy, C Hackman, R Nelson (2008). "The Physical Basis of the Leap Second". Astronomical Journal 136 (5): 1906–1908. Bibcode 2008AJ....136.1906M. doi:10.1088/0004-6256/136/5/1906. "... the SI second is equivalent to an older measure of the second of UT1, which was too small to start with and further, as the duration of the UT1 second increases, the discrepancy widens." 
21. ^ In the late 1950s, the caesium standard was used to measure both the current mean length of the second of mean solar time (UT2) (9,192,631,830 cycles) and also the second of ephemeris time (ET) (9,192,631,770±20 cycles), see L Essen (1968). "Time Scales". Metrologia 4 (4): 161–165. Bibcode 1968Metro...4..161E. doi:10.1088/0026-1394/4/4/003. http://www.leapsecond.com/history/1968-Metrologia-v4-n4-Essen.pdf. . As noted in page 162, the 9,192,631,770 figure was chosen for the SI second. L Essen in the same 1968 article stated that this value "seemed reasonable in view of the variations in UT2".
22. ^ See page 515 in RA Nelsonet al.; McCarthy, D D; Malys, S; Levine, J; Guinot, B; Fliegel, H F; Beard, R L; Bartholomew, T R (2000). "The leap second: its history and possible future". Metrologia 38 (6): 509–529. Bibcode 2001Metro..38..509N. doi:10.1088/0026-1394/38/6/6. http://www.cl.cam.ac.uk/~mgk25/time/metrologia-leapsecond.pdf. 
23. ^ AD Ludlow et al. (2006). "Systematic study of the ⁸⁷Sr clock transition in an optical lattice". Physical Review Letters 96 (3): 033003. arXiv:physics/0508041. Bibcode 2006PhRvL..96c3003L. doi:10.1103/PhysRevLett.96.033003. 
24. ^ R Wynands, S Weyers (2005). "Atomic fountain clocks". Metrologia 42 (3): S64–S79. Bibcode 2005Metro..42S..64W. doi:10.1088/0026-1394/42/3/S08. 
25. ^ "NIST-F1 Cesium Fountain Atomic Clock". NIST. http://tf.nist.gov/cesium/fountain.htm. Retrieved 2009-08-19. 
26. ^ McCarty, D. D.; Seidelmann, P. K. (2009). TIME From Earth Rotation to Atomic Physics. Weinheim: WILEY-VCH Verlag GmbH & Co.. pp. 68, 232. 

External links

Look up second in Wiktionary, the free dictionary.

Wikimedia Commons has media related to: Second

• National Physical Laboratory: Trapped ion optical frequency standards
• High-accuracy strontium ion optical clock; National Physical Laboratory (2005)
• National Research Council of Canada: Optical frequency standard based on a single trapped ion
• NIST: Definition of the second; notice the cesium atom must be in its ground state at 0 K
• Official BIPM definition of the second
• Seconds and leap seconds by the USNO
• The leap second: its history and possible future
• What is a Cesium atom clock?

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1.
num. - anden
n. - sekundering, støtte
v. tr. - sekundere, støtte
adv. - nummer to

idioms:

• at second hand    på anden hånd, andenhåndsinformation
• second ballot    omvalg, ny afstemning
• second best    næstbedst
• second chamber    andet kammer
• second childhood    gå i barndom
• second coming    Kristi genkomst
• second cousin    halvfætter, halvkusine
• second fiddle    anden violin
• second hand    brugt, antikvarisk
• second honeymoon    anden bryllupsrejse
• second in command    næstkommanderende
• second language    fremmedsprog, andet sprog
• second lieutenant    sekondløjtnant
• second name    efternavn
• second nature    i blodet
• second opinion    anden mening
• second person    anden person
• second sight    sjette sans, clairvoyance, synskhed
• second string    reserve
• second teeth    blivende tænder
• second thoughts    nærmere eftertanke
• second to none    ikke stå tilbage for nogen, kunne måle sig med hvem som helst
• second wind    få pusten, få vejret

2.
n. - sekund

idioms:

• Wait a second    vent et øjeblik

3.
v. tr. - overføre, udlåne, stille til rådighed

Nederlands (Dutch)
tweede, andere, inferieur, ten tweede, seconde, tel, ogenblik, seconderen, steunen (motie), assisteren

Français (French)
1.
n. - (Math, Phys) seconde, instant, deuxième, second, deux (pour une date), (GB, Univ) assez bien, (Aut) deuxième/seconde (vitesse), article à défauts, soigneur (boxe), témoin (d'un duel), (Mus) seconde
adj. - deuxième, second, d'un autre (une opinion)
v. tr. - (gén) seconder, (Sport) être le soigneur de, être le témoin de, (gén) soutenir, appuyer (une idée), (Comm) détacher (de, à)
adv. - deuxièmement

idioms:

• at second hand    deuxièmement
• second ballot    deuxième tour du scrutin
• second best    faute de mieux, pis aller
• second chamber    chambre haute
• second childhood    deuxième enfance
• second coming    second avènement
• second cousin    cousin issu de germains
• second fiddle    deuxième violon, rôle secondaire
• second hand    d'occasion, de seconde main
• second honeymoon    seconde lune de miel
• second in command    (Mil) commandant en second, (gén) second, adjoint
• second language    deuxième langue
• second lieutenant    (Mil) sous-lieutenant
• second name    nom de famille, deuxième prénom
• second nature    seconde nature
• second opinion    seconde opinion
• second person    deuxième personne
• second sight    clairvoyance
• second string    (avoir) plus d'une corde à son arc
• second teeth    dent définitive
• second to none    imbattable, sans pareil
• second wind    second souffle

2.
n. - seconde

idioms:

• Wait a second    un instant (excl)

3.
v. tr. - (Mil) détacher (de, à)

Deutsch (German)
1.
num. - Zweite
n. - Sekunde, Zweiter, Sekundant
v. - sekundieren, unterstützen, abstellen
adv. - unterstützen

idioms:

• at second hand    gebraucht
• second ballot    Stichwahl
• second best    Zweitbester
• second chamber    zweite Kammer
• second childhood    Altersschwachsinn
• second coming    zweite Ankunft
• second cousin    Cousin zweiten Grades
• second fiddle    zweite Geige
• second hand    Sekundenzeiger
• second honeymoon    zweite Flitterwochen
• second in command    stellvertretender Kommandeur
• second language    zweite Fremdsprache
• second lieutenant    Leutnant
• second name    Nachname, Zuname
• second nature    zweite Natur
• second opinion    Meinung eines weiteren Sachverständigen
• second person    zweite Person
• second sight    das Zweite Gesicht
• second string    zweites Eisen im Feuer
• second teeth    Zähne, die die Milchzähne bei Säugetieren ersetzen
• second to none    unübertroffen
• second wind    neuer Auftrieb

2.
n. - Sekunde

idioms:

• Wait a second    einen Moment!

3.
v. - abstellen, zeitweilig versetzen

Ελληνική (Greek)
adj. - δεύτερος, υποδεέστερος, πρόσθετος
n. - δευτερόλεπτο, δεύτερος, βοηθός αγωνιζομένου, μάρτυρας μονομαχίας, (χρονική) στιγμή, δεύτερη ταχύτητα (αυτοκινήτου κ.λπ.), (μουσ.) άλτο, (πληθ.) είδη δεύτερης ποιότητας, (πληθ.) δεύτερη μερίδα
v. - υποστηρίζω, (στρατ.) αποσπώ
num. - δεύτερος

idioms:

• at second hand    από δεύτερο χέρι, έμμεσα
• second ballot    δεύτερη ψηφοφορία
• second best    αμέσως καλύτερος, υποδεέστερος, επιλαχών
• second chamber    'Ανω Βουλή
• second childhood    δεύτερη νεότητα, ξεμώραμα
• second coming    δευτέρα παρουσία
• second cousin    δεύτερος εξάδελφος
• second fiddle    δεύτερο βιολί, (μτφ.) δευτερεύων ρόλος
• second hand    (από) δεύτερο χέρι, δευτερολεπτοδείκτης, μεταχειρισμένος, (κατάστημα) μεταχειρισμένων ειδών
• second honeymoon    δεύτερο ταξίδι του μέλιτος
• second in command    υπαρχηγός, (στρατ.) υποδιοικητής
• second language    δεύτερη/ξένη γλώσσα
• second lieutenant    (στρατ.) ανθυπολοχαγός
• second name    επώνυμο
• second nature    δευτέρα φύσις
• second opinion    δεύτερη γνώμη
• second person    (γραμμ.) δεύτερο πρόσωπο
• second sight    διαίσθηση, ενόραση, διορατικότητα
• second string    δεύτερη/εναλλακτική λύση, δεύτερη δουλειά
• second teeth    δεύτερα (μόνιμα) δόντια
• second thoughts    αναθεώρηση απόψεων, ωριμότερη σκέψη
• second to none    ασυναγώνιστος, άριστος
• second wind    ξανάσασμα, ανανέωση (δυνάμεων)
• Wait a second    μια στιγμή!

Italiano (Italian)
assecondare, spalleggiare, appoggiare, distaccare, in secondo luogo, secondo, assistente, seconda

idioms:

• at second hand    di seconda mano
• second ballot    seconda votazione
• second best    mediocre
• second chamber    camera dei deputati
• second childhood    seconda infanzia
• second coming    secondo Avvento
• second cousin    cugino di secondo grado
• second fiddle    secondo violino
• second hand    lancetta dei minuti
• second honeymoon    seconda luna di miele
• second in command    vicecomandante
• second language    seconda lingua
• second lieutenant    sottotenente
• second name    secondo nome
• second nature    seconda natura
• second opinion    seconda opinione
• second person    seconda persona
• second sight    veggenza
• second string    secondo violino
• second teeth    denti permanenti
• second thoughts    ripensamenti
• second to none    incontestabilmente primo
• second wind    nuova energia, ritorno di forze

Português (Portuguese)
adj. - segundo
n. - segundo (m), assistente (m), testemunha (f)
v. - secundar
num. - segundo

idioms:

• at second hand    em segunda mão
• second ballot    segunda apuração
• second best    segundo melhor
• second chamber    segunda câmara
• second childhood    segunda infância
• second coming    segundo lugar
• second cousin    primo em segundo grau
• second fiddle    desempenhar papel secundário
• second hand    em segunda mão
• second honeymoon    segunda lua de mel
• second in command    segundo no comando
• second language    segundo idioma
• second lieutenant    segundo tenente
• second name    segundo nome
• second nature    segunda natureza
• second opinion    segunda opinião
• second person    segunda pessoa
• second sight    segunda visão
• second string    reserva de time
• second teeth    segundo dente
• second thoughts    outros pensamentos
• second to none    não ser superado por ninguém
• second wind    tomar fôlego para continuar

Русский (Russian)
секунда, момент, второй, помощник, получивший вторую премию, секундант, второй класс (какого-л. транспорта), товар второго сорта, второе (блюдо), второй (по счету, по времени), повторный, второстепенный, другой, еще один, дополнительный, уступающий (в чем-л.), второсортный, во-вторых, выступать в поддержку, быть секундантом

idioms:

• at second hand    из вторых рук, понаслышке
• second ballot    второй тур голосования
• second best    по качеству уступающий только первому, занимающий второе место
• second chamber    вторая палата (парламента)
• second childhood    старческий маразм, второе детство
• second coming    второе пришествие
• second cousin    троюродный брат, троюродная сестра
• second fiddle    "вторая скрипка ", человек,занимающий подчиненнае положение
• second hand    посредник, ближайший помощник, секундная стрелка, подержанный, заимствованный, неоригинальный, из вторых рук
• second honeymoon    второй медовый месяц
• second in command    заместитель командира
• second language    второй язык, язык, наиболее распространенный в стране, не считая национального
• second lieutenant    второй лейтенант
• second name    фамилия, второе имя (данное при крещении)
• second nature    вторая натура
• second opinion    другое мнение
• second person    второе лицо
• second sight    ясновидение
• second string    дублирующий
• second teeth    постоянные зубы
• second thoughts    мысли, пришедшие в голову после размышления, переоценка
• second to none    никем не превзойденный
• second wind    второе дыхание, прилив новых сил

Español (Spanish)
1.
n. - en segundo lugar, segundo
adj. - segundo, mediocre, secundario, inferior, de los segundos
v. tr. - secundar, apoyar, asistir
adv. - en segundo lugar, en segunda clase

idioms:

• at second hand    de segunda mano, indirectamente, por medio de un intermediario
• second ballot    segunda votación
• second best    segundo, mejor después del primero
• second chamber    cámara alta (del parlamento)
• second childhood    la segunda infancia, senilidad, chochez
• second coming    el segundo retorno de Jesucristo
• second cousin    primo segundo
• second fiddle    desempeñar un papel secundario
• second hand    manecilla, segundero
• second honeymoon    segunda luna de miel
• second in command    segundo en jefe, subjefe
• second language    segunda lengua
• second lieutenant    subteniente, alférez
• second name    apellido
• second nature    segunda naturaleza
• second opinion    segunda opinión
• second person    segunda persona
• second sight    clarividencia, doble vista
• second string    inferior en calidad o rango, jugador suplente, curso de acción alternativo
• second teeth    segunda dentición
• second to none    no ser inferior a nadie, no ir a la zaga de nadie, sin comparación
• second wind    fuerzas que se recuperan después de un arduo esfuerzo físico

2.
n. - segundo, momento, instante

idioms:

• Wait a second    ¡un momento!, ¡momentito!, espera un momento

3.
v. tr. - (mil) trasladar temporalmente

Svenska (Swedish)
adj. - andra, ännu en, en till, underlägsen, sekunda, sekundär
n. - tvåa, andra man, sekund, ögonblick, tvåans växel, tvåan, sekundant, medhjälpare
v. - understödja, biträda, ansluta sig till, instämma i, sekundera, detachera, avdela
adj. - näst, andra klass, som tvåa som nummer två i ordn
num. - andra

中文（简体）(Chinese (Simplified))
1. 秒, 瞬间, 片刻

idioms:

• at second hand    问接地
• second ballot    第二次投票
• second best    第二好
• second chamber    上议院
• second childhood    第二童年, 老年昏聩状态
• second coming    再来, 再临, 世界末日前的基督复临
• second cousin    堂兄弟姊妹, 远房堂兄弟姊妹, 表兄弟姊妹
• second fiddle    候补的角色
• second hand    中间人, 助手, 旧货
• second honeymoon    二度密月
• second in command    次将, 副将, 副司令, 第二把手
• second language    第二门语言, 第二语言
• second lieutenant    少尉
• second name    姓, 另一个名字
• second nature    第二天性, 老习惯
• second opinion    其他人的意见
• second person    第二人称
• second sight    洞察力, 千里眼
• second string    替补队员, 二线队员, 替补的, 候补的
• second teeth    成人齿, 永久齿
• second thoughts    重新考虑
• second to none    不比任何人差, 首屈一指的
• second wind    重新振作, 恢复精神, 恢复元气
• Wait a second    等一会儿

2. 第二的, 二等的, 次等的, 第二次的, 次要的, 从属的, 副的, 第二名, 二等奖, 第二位, 助手, 另一人, 支持人, 赞成, 支持, 居第二位, 第二, 其次

中文（繁體）(Chinese (Traditional))
1.
n. - 秒, 瞬間, 片刻

idioms:

• at second hand    問接地
• second ballot    第二次投票
• second best    第二好
• second chamber    上議院
• second childhood    第二童年, 老年昏聵狀態
• second coming    再來, 再臨, 世界末日前的基督復臨
• second cousin    堂兄弟姊妹, 遠房堂兄弟姊妹, 表兄弟姊妹
• second fiddle    候補的角色
• second hand    中間人, 助手, 舊貨
• second honeymoon    二度密月
• second in command    次將, 副將, 副司令, 第二把手
• second language    第二門語言, 第二語言
• second lieutenant    少尉
• second name    姓, 另一個名字
• second nature    第二天性, 老習慣
• second opinion    其他人的意見
• second person    第二人稱
• second sight    洞察力, 千里眼
• second string    替補隊員, 二線隊員, 替補的, 候補的
• second teeth    成人齒, 永久齒
• second thoughts    重新考慮
• second to none    不比任何人差, 首屈一指的
• second wind    重新振作, 恢復精神, 恢復元氣
• Wait a second    等一會兒

2.
adj. - 第二的, 二等的, 次等的, 第二次的, 次要的, 從屬的, 副的
n. - 第二名, 二等獎, 第二位, 助手, 另一人, 支援人
v. tr. - 贊成, 支援
adv. - 居第二位, 第二, 其次

한국어 (Korean)
1.
num. - 제2의, 또 하나의, 보조의
n. - 두 번째의 것, 제2세, 보좌관
v. tr. - 후원하다, (목표 등을) 보강하다, 찬성하다
adv. - 둘째로, 다음으로, (교통기관에서) 2등으로

idioms:

• at second hand    조수, 조력자

2.
n. - 초 , 매우 짧은 시간, ~하자 곧

3.
v. tr. - (장교의) 부대 소속을 해제하다, 소속을 임시로 바꾸다

日本語 (Japanese)
n. - 第二のもの, 二世, 第二日, 二塁, 二流品, セカンド, 介添え人, セコンド, 秒, ちょっとの間, 瞬間
adj. - 第二の, もうひとつの, 代わりの, 低音部の, 副次的な, 二流の
v. - 後援する, 支持する, 賛成する, 介添えをする, セコンドを務める
adv. - 第二に

idioms:

• at second hand    中間体を介して, 古物で, また聞きで, 間接に
• in the second place    第二に
• on second thought    考え直して
• second ballot    決選投票
• second best    次善の策, 次位のもの, 次位に
• second chamber    第二院
• second childhood    耄碌
• second coming    再臨
• second cousin    またいとこ
• second fiddle    第二ヴァイオリン, 従属的な役割
• second hand    秒針, 助力者, 助手
• second honeymoon    結婚後の旅行
• second in command    次将, 副将
• second language    第二公用語, 第二の言語
• second lieutenant    少尉
• second name    姓
• second nature    第二の天性
• second opinion    もう一つの意見
• second person    第二人称, 第二位格
• second sight    千里眼, 予知能力
• second string    もう一つの手段
• second teeth    永久歯
• second thoughts    考え直し
• second to none    だれにも劣らない
• second wind    第二呼吸, 新たな精力

العربيه (Arabic)
‏(صفه) أضافي, ثاني (الاسم) لحظه, ثانيه (فعل) يؤيد, يناصر (صفه) أضافي, ثاني (عدد) ألثاني‏

עברית (Hebrew)
n. - ‮תמיכה, נושא-כלים, עוזר למתאגרף בעת תחרות, קמח גס או לחם הנאפה ממנו, ציון בינוני, המנה השנייה בארוחה, אקורד המשתרע על פני טונים סמוכים‬
adj. - ‮שני‬
v. tr. - ‮תמך, צידד ב-, הצביע בעד, עזר, העביר (זמנית) לתפקיד‬
adv. - ‮שני, נוסף, אחר, שנית, משני‬
n. - ‮שנייה, רגע‬
v. tr. - ‮העביר (זמנית) לתפקיד‬

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