1. a small metal instrument specially cut to fit into a lock and move its bolt.
2. any of various devices resembling or functioning as a key.
3. something that affords a means of access: the key to happiness.
4. something that secures or controls entrance to a place.
5. something that affords a means of clarifying a problem.
6. a book, pamphlet, or other text containing the solutions or translations of material given elsewhere, as testing exercises.
7. a systematic explanation of abbreviations, symbols, etc., used in a dictionary, map, etc.
8. the system, method, pattern, etc., used to decode or decipher a cryptogram, as a code book, machine setting, or key word.
9. one of a set of marked parts, designated areas, or levers pressed in operating a typewriter, computer terminal, calculator, etc.
10.a manually operated lever for opening and closing an electric circuit, used to produce signals in telegraphy.
a. (in a keyboard instrument) one of the levers that when depressed by the performer sets in motion the playing mechanism.
b. (on a woodwind instrument) a metal lever that opens and closes a vent.
c. the relationship perceived between all tones in a given unit of music and a single tone or a keynote; tonality.
d. the principal tonality of a composition: a symphony in the key of C minor.
e. the keynote or tonic of a scale.
12.tone or pitch, as of voice.
13.mood or characteristic style, as of expression or thought.
14.degree of intensity, as of feeling or action.
15.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.
16.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.
17.a contrivance for grasping and turning a bolt, nut, etc.
18.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.
19.(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.
a. a device for opening and closing electrical contacts.
b.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.
21.Biology. a systematic tabular classification of the significant characteristics of the members of a group of organisms to facilitate identification and comparison.
22.Masonry. a keystone.
23.Architecture. (in a ribbed vault) a stone, as a boss, at the intersection of two or more ribs.
24.Masonry, Carpentry. a wedge, as for tightening a joint or splitting a stone or timber.
25.Carpentry. a small piece of wood set into a timber across the grain to prevent warping.
26.Building Trades. any grooving or roughness applied to a surface to improve its bond with another surface.
27.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.
28.Painting. the tonal value and intensity of a colour or range of colours.
29.Botany. a Samara.
30.(initial capital letter) a member of the House of Keys.
31.keys, spiritual authority.–adj.
32.chief; major; important; essential; fundamental; pivotal.–verb (used with object)
33.to regulate or adjust (actions, thoughts, speech, etc.) to a particular state or activity; bring into conformity.
34.Music. to regulate the key or pitch of.
a. to paint (a picture) in a given key.
b. to adjust the colours in (a painting) to a particular hue.
36.to fasten, secure, or adjust with a key, wedge, or the like, as parts of a mechanism.
37.to provide with a key.
38.(in the layout of newspapers, magazines, etc.) to identify, through signs or symbols, the positions of illustrations or pieces of copy in a dummy.
39.to lock with or as if with a key.
40.Masonry. to provide (an arch or vault) with a keystone.–verb (used without object)
41.to use a key.
The thief of Time has many keys