a small metal instrument specially cut to fit into a lock and move its bolt.

any of various devices resembling or functioning as a key

the key of a clock.

key card.

something that affords a means of access

the key to happiness.

something that secures or controls entrance to a place

Gibraltar is the key to the Mediterranean.

something that affords a means of clarifying a problem.

a book, pamphlet, or other text containing the solutions or translations of material given elsewhere, as testing exercises.

a systematic explanation of abbreviations, symbols, etc., used in a dictionary, map, etc.

pronunciation key. Compare legend def. 4

the system, method, pattern, etc., used to decode or decipher a cryptogram, as a code book, machine setting, or key word.

one of a set of marked parts, designated areas, or levers pressed in operating a typewriter, computer terminal, calculator, etc.

a manually operated lever for opening and closing an electric circuit, used to produce signals in telegraphy.

Music .

(in a keyboard instrument) one of the levers that when depressed by the performer sets in motion the playing mechanism.

(on a woodwind instrument) a metal lever that opens and closes a vent.

the relationship perceived between all tones in a given unit of music and a single tone or a keynote; tonality.

the principal tonality of a composition

a symphony in the key of C minor.

the keynote or tonic of a scale.

tone or pitch, as of voice

to speak in a high key.

mood or characteristic style, as of expression or thought

He writes in a melancholy key.

degree of intensity, as of feeling or action.

a pin, bolt, wedge, or other piece inserted in a hole or space to lock or hold parts of a mechanism or structure together; a cotter.

a small piece of steel fitting into matching slots of a hub of a wheel or the like and the shaft on which the wheel is mounted so that torque is transmitted from one to the other.

a contrivance for grasping and turning a bolt, nut, etc.

Computers . a field or group of characters within a record that identifies the record, establishing its position among sorted records, and/or provides information about its contents.

(in a series of advertisements or announcements soliciting replies) a unique code inserted for each medium used, to determine the relative effectiveness of the media.

Electricity .

a device for opening and closing electrical contacts.

a hand-operated switching device ordinarily formed of concealed spring contacts with an exposed handle or push button, capable of switching one or more parts of a circuit.

Biology . a systematic tabular classification of the significant characteristics of the members of a group of organisms to facilitate identification and comparison.

Masonry . a keystone.

Architecture . (in a ribbed vault) a stone, as a boss, at the intersection of two or more ribs.

Masonry, Carpentry . a wedge, as for tightening a joint or splitting a stone or timber.

Carpentry . a small piece of wood set into a timber across the grain to prevent warping.

Building Trades . any grooving or roughness applied to a surface to improve its bond with another surface.

Basketball . keyhole ( def. 2 ) .

Photography . the dominant tonal value of a picture, a high-key picture having light tonal values and minimal contrast and a low-key picture being generally dark with minimal contrast.

Painting . the tonal value and intensity of a color or range of colors

Rembrandt's colors are characterized by their low key.

Botany . a samara.

( initial capital letter ) a member of the House of Keys.

keys, spiritual authority.

chief; major; important; essential; fundamental; pivotal

a key person in the company; key industries.

to regulate or adjust (actions, thoughts, speech, etc.) to a particular state or activity; bring into conformity

to key one's speech to the intellectual level of the audience.

Music . to regulate the key or pitch of.

Painting .

to paint (a picture) in a given key.

to adjust the colors in (a painting) to a particular hue

He keyed the painting to brown.

to fasten, secure, or adjust with a key, wedge, or the like, as parts of a mechanism.

to provide with a key.

(in the layout of newspapers, magazines, etc.) to identify, through signs or symbols, the positions of illustrations or pieces of copy in a dummy.

to lock with or as if with a key.

Masonry . to provide (an arch or vault) with a keystone.

Computers . keyboard ( def. 4 ) .

to use a key.

Computers . keyboard ( def. 4 ) . ?

key in, Computers . keyboard ( def. 4 ) .

key on,

Football . to watch the position and movements of an opponent in order to anticipate a play

The defensive backs keyed on the star receiver.

Also, key in on. to single out as of prime importance or interest; be intent on or obsessed with

a company that is keyed in on growth.

key up,

to bring to a particular degree of intensity of feeling, excitement, energy, nervousness, agitation, etc.

keyed up over the impending test.

to raise (a piece of masonry) by the insertion of a wedge or wedges.

to raise (the haunches of an arch) by the insertion of a voussoir. ?

power of the keys, the authority of a pope in ecclesiastical matters

vested in him as successor of St. Peter.

adjective

inessential , insignificant , nonessential , unimportant

noun

lock , question

adjective

basic , chief , crucial , decisive , fundamental , indispensable , leading , main , major , material , pivotal , primary , principal , vital , capital , cardinal , first , foremost , number one , paramount , premier , prime , top , central

noun

latchkey , opener , passkey , screw * , skeleton , blueprint , brand , cipher , clue , code , core , crux , cue , earmark , explanation , fulcrum , guide , hinge , index , indicator , interpretation , lead , lever , marker , means , nexus , nucleus , passport , password , pivot , pointer , root , sign , symptom , ticket , translation , formula , route , secret , address , answer , atoll , cay , central , critical , digital , essential , important , island , isle , islet , main , pitch , pivotal , quay , reef , scale , solution , tonality , vital