key¹ (kē)
n., pl., keys.

1. 1. A notched and grooved, usually metal implement that is turned to open or close a lock.
   2. A similar device used for opening or winding: the key of a clock; a can that has a key attached.
2. A means of access, control, or possession.
3. 1. A vital, crucial element.
   2. A set of answers to a test.
   3. A table, gloss, or cipher for decoding or interpreting.
4. A device, such as a wedge or pin, inserted to lock together mechanical or structural parts.
5. Architecture. The keystone in the crown of an arch.
6. 1. A button or lever that is depressed to operate a machine.
   2. A button that is depressed to cause a corresponding character or function to be typed or executed by a typewriter or to be accepted as input by a computer.
   3. Music. A button or lever that is depressed with the finger to produce or modulate the sound of an instrument, such as a clarinet or piano.
7. Music.
   1. A tonal system consisting of seven tones in fixed relationship to a tonic, having a characteristic key signature and being the structural foundation of the bulk of Western music; tonality.
   2. The principal tonality of a work: an etude in the key of E.
8. The pitch of a voice or other sound.
9. A characteristic tone or level of intensity, as of a speech or sales campaign. Often used in combination: high-key; low-key.
10. Botany. A samara.
11. An outline of the distinguishing characteristics of a group of organisms, used as a guide in taxonomic identification.
12. Basketball. An area at each end of the court between the base line and the foul line and including the jump-ball circle at the foul line: a jump shot from the top of the key.

adj.
Of crucial importance; significant: key decisions; the key element of the thesis.


v., keyed, key·ing, keys.

v.tr.

1. To lock with or as if with a key.
2. Architecture. To furnish (an arch) with a keystone.
3. Music. To regulate the pitch of.
4. To bring into harmony; adjust or adapt.
5. To supply an explanatory key for.
6. 1. To operate (a device), as for typesetting, by means of a keyboard.
   2. To enter (data) into a computer by means of a keyboard.
7. To identify (a biological specimen).
8. To vandalize or mar by scratching with a key: Vandals keyed the cars left in the parking garage.

v.intr.

1. To pay close attention; focus: improved service by keying on customer complaints; keyed in on the main points of the lecture.
2. Sports. To watch or cover an opposing player closely in an effort to limit the player's effectiveness. Used with on: "[She] still carries the burden of scoring ... even though opponents key on her throughout every game" (Josh Barr).

phrasal verb:

key up

1. To make intense, excited, or nervous.

idioms:

in key

1. In consonance with other factors.

out of key

1. Not in consonance with other factors.

[Middle English kai, kei, from Old English cǣg.]

key² (kē)
n., pl., keys.
A low offshore island or reef, especially in the Gulf of Mexico; a cay.

[Alteration (influenced by key , variant of QUAY) of Spanish cayo; see cay.]

key³ (kē)
n. Slang, pl., keys.
A kilogram of marijuana, cocaine, or heroin.

[Shortening and alteration of KILOGRAM.]

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The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.

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