complement

(kŏm'plə-mənt)
n.

1. 1. Something that completes, makes up a whole, or brings to perfection.
   2. The quantity or number needed to make up a whole: shelves with a full complement of books.
   3. Either of two parts that complete the whole or mutually complete each other.
2. An angle related to another so that the sum of their measures is 90°.
3. Grammar. A word or words used to complete a predicate construction, especially the object or indirect object of a verb; for example, the phrase to eat ice cream in We like to eat ice cream.
4. Music. An interval that completes an octave when added to a given interval.
5. The full crew of officers and enlisted personnel required to run a ship.
6. Immunology. A complex system of proteins found in normal blood plasma that combines with antibodies to destroy pathogenic bacteria and other foreign cells. Also called alexin.
7. Mathematics & Logic. For a universal set, the set of all elements in the set that are not in a specified subset.
8. A complementary color.

tr.v., -ment·ed, -ment·ing, -ments. (-mĕnt')
To serve as a complement to: Roses in a silver bowl complement the handsome cherry table.

[Middle English, from Old French, from Latin complēmentum, from complēre, to fill out. See complete.]

USAGE NOTE   Complement and compliment, though quite distinct in meaning, are sometimes confused because they are pronounced the same. As a noun, complement means "something that completes or brings to perfection" (The antique silver was a complement to the beautifully set table); used as a verb it means "to serve as a complement to." The noun compliment means "an expression or act of courtesy or praise" (They gave us a compliment on our beautifully set table), while the verb means "to pay a compliment to."

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is a term in grammar for a word or phrase added to a to complete the predicate of a sentence. (In the examples that follow, the complement is in bold type.) The most common form of complement is the type that follows a of state such as be, look, seem, etc.: I am his brother / She looked lovely / You seem to be unhappy / They remained out of reach. A complement can also relate to the object of a sentence rather than its subject (He called his mother a fool), and the term is sometimes extended to include words and phrases that complete the sense of other words, e.g. adjectives (fond of chocolate) and prepositions (over the moon).

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For more information on complement, visit Britannica.com.

A group of proteins in the blood and body fluids that play an important role in humoral immunity and the generation of inflammation. When activated by antigen-antibody complexes, or by other agents such as proteolytic enzymes (for example, plasmin), complement kills bacteria and other microorganisms. In addition, complement activation results in the release of peptides that enhance vascular permeability, release histamine, and attract white blood cells (chemotaxis). The binding of complement to target cells also enhances their phagocytosis by white blood cells. The most important step in complement system function is the activation of the third component of complement (C3), which is the most abundant of these proteins in the blood.

Genetic deficiencies of certain complement subcomponents have been found in humans, rabbits, guinea pigs, and mice. Certain deficiencies lead to immune-complex diseases, such as systemic lupus erythematosus; other deficiencies result in increased susceptibility to bacterial infections, particularly those of the genus Neisseria (for example, gonorrhea and meningococcal meningitis), and hereditary angioneurotic edema. See also Complement-fixation test; Immunity.

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The number derived by subtracting a number from a base number. For example, the tens complement of 8 is 2. In set theory, complement refers to all the objects in one set that are not in another set.

Complements are used in digital circuits, because it is faster to subtract by adding complements than by performing true subtraction. The binary complement of a number is created by reversing all bits and adding 1. The carry from the high-order position is eliminated. The following example subtracts 5 from 8.

     Decimal    Binary    Complement
      8          1000      1000
     -5         -0101     +1011
     __         _____     _____
      3          0011      0011

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noun

1. Something that completes another: supplement. See agree/disagree, part/whole.
2. Something added to another for embellishment or completion: accompaniment, enhancement, enrichment. See accompanied.

verb

To supply what is lacking: complete, fill in (or out), round (off or out), supplement. See agree/disagree, part/whole.

v

Definition: complete
Antonyms: take away

The difference between an octave and a given simple interval, hence the INVERSION of that interval at the octave; the complement of a perfect 5th is a perfect 4th.

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The complement of a set S is the class of objects that are not members of S. In standard set theory the complement of a set cannot itself be a set: only those things not in the set but meeting some further restriction can form a set. See separation, axiom of.

The collective term for proteins of the complement system, known separately as Cl, C2, C3, etc. The serum complement tends to be deficient in some endurance athletes. This may contribute to their increased susceptibility to infection.

A good or service that is used in conjunction with another good or service. Usually, the complementary good has little to no value when consumed alone but, when combined with another good or service, it adds to the overall value of the offering. Also, good tends to have more value when paired with a complement than it does by itself.

Investopedia Says:
A product can be considered a complement when it shares a beneficial relationship with another product offering. In an economic sense, when the price of a good rises, the demand for its complement will fall because consumers don't want to use the complement alone. 

For example, if the price of hot dogs rises so much that people stop consuming them, this will also cause a decrease in demand for hot dog buns. Because the price of hot dogs has an inverse relationship to the demand for hot dog buns, we call them complementary products.

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IN BRIEF: To make whole.

Courage is the complement of fear. A man who is fearless cannot be courageous. (He is also a fool.) — Robert Heinlein (1907-1988).

Tutor's tip: I had to "compliment" (express approval or praise) the chef on what an excellent "complement" (something that goes well with something else) the potatoes made to the roast beef.

LearnThatWord.com is a free vocabulary and spelling program where you only pay for results!

or (formerly) alexin(e)

a system of proteins and cell receptors, found in the plasma of vertebrates, that participates in immune defence against infection by microorganisms; the activation products of complement components cause lysis of antigenic cells, attract phagocytic cells to the site of activation, and assist the uptake and destruction of antigenic cells by phagocytes. Complement is also involved in immunological tissue injury. The plasma components comprise a recognition unit, three alternative pathways for activation of C3 (the classical pathway uses C2 and C4), and a terminal pathway that ends in the formation of the membrane attack complex (C356789). Synthesis occurs mainly in hepatocytes and that of several components is regulated by interleukins 1 and 6, tumour necrosis factor, γ interferon, and endotoxic polysaccharide. The plasma components amount to about 2000 mg L⁻¹ (C1 ≈250, C3 ≈1200, C4 ≈400 mg L⁻¹). The components of complement, mostly β- or γ-globulins, are generally designated by the symbol C and an identifying suffixed numeral. There are three alternative pathways for activation of complement, and these probably work together. The classical pathway is followed below. The alternative pathway uses properdin and factors B and D to activate C3 and C5. The lectin pathway utilizes mannose-binding protein and its associated serine protease (MASP), and activates C3 as in the classical pathway but without a requirement for C1.
C1
is a Ca²⁺-dependent complex of C1q, C1r, and C1s in the molar ratio of 1:2:2. C1q has a 'bunch-of-tulips' structure that consists of six collagen-like triple helices each ending in a globular C-terminal domain, which binds the Fc region of immune complexes. Each triple helix consists of homologous A, B, and C chains, which are encoded on neighbouring genes, and contain a collagen-like domain over ≈80% of their length, while the rest contributes to the C-terminal globular head. C1r and C1s are highly homologous serine protease zymogens (83 kDa per subunit). Two subunits of each bind C1q in a calcium-dependent but noncovalent manner. Binding of ligand to C1q causes a conformational change in, and autocatalytic activation of, C1r (EC 3.4.21.41), which then cleaves and activates C1s. The natural substrates for C1s are C2 and C4. Deficiency of A, B, or C chains of C1q results in the clinical phenotype of lupus erythematosus. Deficiency of C1r or C1s also leads to this phenotype or to glomerulonephritis.
C2
is a single-chain polypeptide (102 kDa) that is highly homologous with factor B. C1s releases a small peptide (S2b) and (active) C2a. C2a and C4b form a bimolecular enzyme called C3 convertase, a serine proteinase (EC 3.1.21.43). Deficiency of C2 results in rheumatic disorders and pyogenic infections.
C3
is a glycoprotein (185 kDa) that consists of an α chain linked by a disulfide bond to a β chain, both being derived from the same precursor, which is homologous with C4 and C5. The α chain contains an intrachain thiol ester that is important for the function of C3. C3 convertase (i.e. C4b2a) cleaves a small peptide, which is the N-terminal region of the α chain, to expose the thiol ester. C3a is an anaphylatoxin. The rest of the molecule (C3b) binds covalently (through the thiol ester) to cell surfaces or the immune complex, and in complex with C3 convertase forms C4b2a3b, which is called C5 convertase. Deficiency of C3 leads to rheumatic disorders and pyogenic infections.
C4
is a glycoprotein (200 kDa) that consists of disulfide bond-linked α, β, and γ chains, all derived from the same precursor, which is homologous to those of C3 and C5. The α chain contains an intrachain thiol ester, which is important for the function of C4. C1s releases C4a, the N-terminal portion of the α chain, and exposes the thiol ester. This binds covalently to cell surfaces or to immune complexes. The rest of the molecule is C4b, which with C2a forms C4b2a, or C3 convertase. In combination with C3b, C3 convertase forms C4b2a3b, which is C5 convertase. Deficiency of C4 leads to a lupus e rythematosus phenotype. The human form is polymorphic, the allotype being C4a. C4a alleles carry blood group Rogers and C4b alleles carry Chido. Total deficiency of C4a6 allotype is associated with hemolytic disease.
C5
is a glycoprotein (190 kDa) that consists of an α chain linked by a disulfide bond to a β chain, both derived from a precursor homologous to those of C3 and C4. C5 convertase (i.e. C4b2a3b) releases a small anaphylatoxic and leukocyte-attractant peptide (C5a), which is the N-terminal region of the α chain. Activation of C5 initiates the spontaneous assembly of the late complement components, C5 — C9, into the membrane attack complex (see MAC (def. 1)). C5b recruits a molecule of each of C6, C7, and C8, which insert their hydrophobic regions into the target cell membrane. Deficiency of C5 leads to meningococcal infection.
C6, C7, C8, and C9,
together with C5b, constitute the membrane attack complex; all are structurally related and similar to perforin. C6 is a single-chain polypeptide (128 kDa) that interacts with C5b, C7, and C8. C7 is a single-chain polypeptide that interacts with C5b, C6, and C8. C8 is a heterotrimer comprising: α, β, and γ subunits. An α chain is linked by a disulfide bond to a γ chain, and a β chain then links to these two chains. C8 interacts with C5b, C6, and C7, the complex inserting into the target cell membrane. C9 is a single-chain polypeptide (70 kDa). From 1 to 18 molecules of C9 are recruited by the C5b678 complex to form a tubular transmembrane channel that disturbs the target cell membrane and increases its permeability. It is cleaved by thrombin to form C9a and C9b. Deficiency of C6, C7, C8, or C9 is associated with meningococcal infection.
Factor B
, a zymogen of M_r 100 000, is activated by factor D, which selectively cleaves an Arg-∣-Lys bond when factor B is complexed with C3b to form factor Bb. Following cleavage the C3b-Bb complex acts as alternative-complement-pathway C3/C5 convertase (EC 3.4.21.47), which can convert C3 to C3a and C3b by cleaving an Arg-∣-Ser bond, and C5 to C5a and C5b by cleavage of an Arg-∣-Xaa bond.
Factor D̄
is a serine proteinase (EC 3.4.21.46) of M_r 24 000; its concentration in human plasma is approximately 1.5 mg L⁻¹.
Factor H
is a cofactor for factor I (EC 3.4.21.45), a serine proteinase that cleaves the α chains of C4b and C3b in the presence of the cofactors for C4-binding.
Properdin
, a glycoprotein of M_r 220 000, is composed of four, probably identical, noncovalently linked polypeptide chains. Two alternative reaction cascades for the activation of complement exist. In the so-called classical pathway, activation (which requires both Ca²⁺ and Mg²⁺) is initiated by the binding of the C1q moiety of C1 to the C_H2 regions of antibody molecules in antibody-antigen aggregates or in antibody bound to cells, thus causing C1 to be converted to a proteinase, C1̄. C1̄ activates C4 and C2 leading to the formation of C3 convertase, a complex proteinase, C42̅, consisting of the activated components C4̄ and C2̄. C42̅ splits C3 to the chemotactic and anaphylatoxic fragment C3a and the fragment C3̄, C3b, which associates with C42̅ to give a



complex, C5 convertase. The latter is a complex proteinase that in turn splits C5 to C5̄ and the chemotactic and anaphylatoxic fragment C5a. In the so-called alternative pathway, activation (which requires Mg²⁺ but not Ca²⁺) is initiated by polysaccharides such as those present on bacterial and yeast cell walls. The proteinase D̄ is analogous to C1̄ but is normally present in serum, where it causes a continuous slow activation, which is greatly enhanced when polysaccharides are present. D̄ acts on B and C3̄ to produce C3B̅, an alternative C3 convertase. C3B̅, which is stabilized by properdin, acts on C3 to produce (C3̄)_nB̄, an alternative C5 convertase. In both pathways, C5̄ production is the last proteolytic step, and there follows a spontaneous association of C5̄ with C6, C7, C8, and C9 to form a lytic complex,



. See also lysine(arginine) carboxypeptidase.

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A complex series of enzymatic proteins occurring in normal serum that are triggered in a cascade manner by, and combine with, the antibody–antigen complexes, producing lysis when the antigen is an intact cell. Complement comprises 25 to 30 discrete proteins, labeled numerically as C1 to C9, and by letters, i.e. B, D, P, etc., and with C1 being divided into subcomponents C1q, C1r and C1s. Components C3 and C5 are involved in the generation of anaphylatoxin and in the promotion of leukocyte chemotaxis, the result of these two activities being the inflammatory response. C1 and C4 are involved in the neutralization of viruses. The components also combine in various sequences to participate in other biological activities, including antibody-mediated immune lysis, phagocytosis, opsonization and anaphylaxis. The complement system is known to be activated by the immunoglobulins IgM and IgG.

• alternate c. pathway, alternative c. pathway — the sequence in which complement components C3 and C5 to C9 are activated without participation by C1, C2 and C4 or the presence of an antibody–antigen complex.
• c. cascade — the sequence of reactions, each being the catalyst for the next, that leads to the terminal complement pathway and cell lysis. There are two pathways for activation of C3, the ‘classical’ (below) and the ‘alternate’ (above).
• classical c. pathway — the one in which all of the complement components C1 to C9 participate and is triggered by antibody–antigen complexes.
• c. deficiency — various complement components may be deficient without serious effects on the host. C3 deficiency is most severe and occurs in humans, Brittany spaniels and Finnish-Landrace lambs. Increased susceptibility to infections results.
• c. fixation tests — utilize antibody–antigen reaction and result in hemolysis to determine the presence of various organisms in the blood. Involves two stages. In the first, also referred to as the test system, antigen is mixed usually with serial dilutions of a test serum in the presence of complement. If the serum contains antibody, i.e. is positive, an antibody–antigen complex is formed which also binds (fixes) complement. In the second stage, also called the indicator system, sheep red blood cells coated with specific, usually rabbit anti-sheep red blood cell antibody are added. The red blood cells are said to be sensitized. If antibody was not present in stage 1, then the free complement lyses the sensitized sheep red blood cells. The basis of many serological tests including those for glanders, tuberculosis and contagious bovine pleuropneumonia. Called also Bordet–Gengou phenomenon. See also immunity.
• c. regulatory proteins — a set of at least seven proteins that are present in plasma (C1 INH, C4b-binding protein, factor H and factor I) or present in cell membranes (decay-accelerating factor [DAF], membrane cofactor protein [MCP] and homologous restriction factor [HHF]) that modulate the complement proteins and protect ‘innocent’ bystander cells and tissues from complement damage.
• terminal c. pathway — the final stages of complement activation in which C5, C6, C7, C8 and C9 are activated; common to both the alternate and classical pathways.

n

One of 11 complex, enzymatic serum proteins. In an antigen-antibody reaction, complement causes lysis. Complement is also involved in anaphylaxis and phagocytosis.

For a list of words related to complement, see:

• Physiology - complement: set of enzymes in bloodstream that work with antibodies to attack foreign cells and bacteria
• Quantities, Relationships, and Operations - complement: angle or arc that when added to another angle or arc equals a right angle
• Grammar and Usage - complement: word or phrase that completes a grammatical construction in the predicate and describes or is identified with the subject or object

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  See crossword solutions for the clue Complement.

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

Dansk (Danish)
n. - besætning, omsagnsled, komplement
v. tr. - komplementere, fuldende

Nederlands (Dutch)
complement, volle bezetting, aanvullen, sluitstuk

Français (French)
n. - (gén, Math, Ling) complément, effectif, personnel
v. tr. - compléter, se compléter

Deutsch (German)
n. - Ergänzung, Vervollkommnung, Vervollständigung
v. - ergänzen, vervollständigen

Ελληνική (Greek)
n. - συμπλήρωμα, παραπλήρωμα, πλήρωμα (σκάφους κ.λπ.), (γραμμ.) κατηγορούμενο ή δεύτερο αντικείμενο, συμπλήρωμα ρήματος

Italiano (Italian)
conclusione, complemento, guarnigione

Português (Portuguese)
n. - complemento (m), totalidade (f), aperfeiçoamento (m), tripulação (f) de navio

Русский (Russian)
дополнение, полный состав

Español (Spanish)
n. - complemento, efectivo
v. tr. - complementar

Svenska (Swedish)
n. - komplement, fullt antal, bestämning (gram.)

中文（简体）(Chinese (Simplified))
补足物, 余角, 补语, 补助, 补足

中文（繁體）(Chinese (Traditional))
n. - 補足物, 餘角, 補語
v. tr. - 補助, 補足

한국어 (Korean)
n. - 보충물, 보어
v. tr. - 보충하다

日本語 (Japanese)
n. - 補足するもの, 補語, 全数, 乗組定員, 補足物
v. - 補って完全にする

العربيه (Arabic)
‏(الاسم) تكمله, تتمه, العدد المقرر لتتمه عمل ما‏

עברית (Hebrew)
n. - ‮השלמה, משלים, תקן מלא‬
v. tr. - ‮השלים‬

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