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key 1

n. pl. keys
a. A notched and grooved, usually metal implement that is turned to open or close a lock.
b. A similar implement or an electronic device used for opening, winding, or starting something: the key of a wind-up alarm clock; the new car's electronic key.
c. A device, such as a wedge or pin, inserted to lock together mechanical or structural parts.
d. A keycard.
2. A determining factor in accomplishing or achieving something: One key to the store's success has been consistent customer service.
a. Something that provides access to or understanding of something else: The key to the mystery was a drug store receipt.
b. A set of answers to a test.
c. A table, gloss, or cipher containing correspondences, as for decoding or interpreting something.
d. Computers A number used by a cryptographic algorithm to encrypt or decrypt data.
4. Architecture The keystone in the crown of an arch.
a. A button or lever that is depressed to operate a machine.
b. 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.
c. 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.
6. Music
a. 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.
b. The principal tonality of a work: an etude in the key of E.
7. The pitch of a voice or other sound.
8. A characteristic tone or level of intensity, as of a speech or sales campaign. Often used in combination: high-key; low-key.
9. Botany A samara.
10. An outline of the distinguishing characteristics of a group of organisms, used as a guide in taxonomic identification.
11. Basketball An area at each end of the court between the baseline and the foul line and including the jump-ball circle at the foul line: a jump shot from the top of the key.
12. The act of replacing portions of a video or photograph containing a preselected color with material from a separate image, as by chroma key.
Of crucial importance; significant: key decisions; the key element of the thesis.
v. keyed, key·ing, keys
1. To lock with a key.
2. To be the determining or crucial factor in: a double that keyed a three-run rally in the fifth inning.
3. Architecture To furnish (an arch) with a keystone.
4. Music To regulate the pitch of.
5. To bring into harmony; adjust or adapt: "achievement tests that are more clearly keyed to what students are held responsible for in high school" (New York Times).
6. To cause to pay attention to: school officials who were keyed into the dietary needs of students.
7. To supply with a key of correspondences or with corresponding references: keyed the pages in the edited book to illustrations in the manuscript.
a. To operate (a device), as for typesetting, by means of a keyboard.
b. To enter (data) into a computer by means of a keyboard.
9. To identify (a biological specimen).
10. To vandalize or mar by scratching with a key: Vandals keyed the cars left in the parking garage.
11. To produce, replace, or include by chroma key.
1. To pay close attention; focus: improved service by keying on customer complaints; keyed into 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).
3. To replace portions of a video or photograph containing a preselected color with material from a separate image, as by chroma key.
Phrasal Verb:
key up
To make intense, excited, or nervous: The actors were keyed up before the opening.
in key
In consonance with other factors.
out of key
Not in consonance with other factors.

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

key 2

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.]

key 3

n. pl. keys Slang
A kilogram of marijuana, cocaine, or heroin.

[Shortening and alteration of kilogram.]


dialect Scot a children's cry for truce or respite from the rules of a game
[origin uncertain]
References in classic literature ?
To-night he had not snapped, and for the first hour or two he lay remarkably still, until at last Mary heard him rattling his bunch of keys against the tin box which he always kept in the bed beside him.
He collected as many keys as he could, and tried all of them during one of those delightful hours which Rosa and Cornelius passed together at the grating of the cell.
More old forgotten keys were probably lying about among the lumber in the sheds.
It is a large key, but the keys of prisons are larger.
By the bye,' it comes into Jasper's mind to say, as he idly examines the keys, 'I have been going to ask you, many a day, and have always forgotten.
You shall speak to the servants," she said, "with the keys of my wardrobe in your hand.
It seems very interesting, love,' said he, lifting his head and turning to where I stood, wringing my hands in silent rage and anguish; 'but it's rather long; I'll look at it some other time; and meanwhile I'll trouble you for your keys, my dear.
A WOLF, who in devouring a man had choked himself with a bunch of keys, asked an ostrich to put her head down his throat and pull them out, which she did.
How had he got into the bedroom--the doors being locked, and the keys being taken away by Mr.
Verily, like a thousand peals of children's laughter cometh Zarathustra into all sepulchres, laughing at those night-watchmen and grave-guardians, and whoever else rattleth with sinister keys.
Let the man remain here; take the keys yourself, and show me the way.
You ought to know more about locks and keys than I do.