key

key - [kee] - /ki/

Noun, plural keys.
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: the key of a clock.
3. key card.
4. something that affords a means of access: the key to happiness.
5. something that secures or controls entrance to a place: Gibraltar is the key to the Mediterranean.
6. something that affords a means of clarifying a problem.
7. a book, pamphlet, or other text containing the solutions or translations of material given elsewhere, as testing exercises.
8. a systematic explanation of abbreviations, symbols, etc., used in a dictionary, map, etc.: pronunciation key.  Compare legend (  def 4 ) .
9. the system, method, pattern, etc., used to decode or decipher a cryptogram, as a code book, machine setting, or keyword.
10. one of a set of marked parts, designated areas, or levers pressed in operating a typewriter, computer terminal, calculator, etc.
11. a manually operated lever for opening and closing an electric circuit, used to produce signals in telegraphy.
12. Music.
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.
13. tone or pitch, as of voice: to speak in a high key.
14. mood or characteristic style, as of expression or thought: He writes in a melancholy key.
15. degree of intensity, as of feeling or action.
16. 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.
17. 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.
18. a contrivance for grasping and turning a bolt, nut, etc.
19. 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.
20. (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.
21. Electricity .
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.
22. Biology . a systematic tabular classification of the significant characteristics of the members of a group of organisms to facilitate identification and comparison.
23. Masonry. a keystone.
24. Architecture . (in a ribbed vault) a stone, as a boss, at the intersection of two or more ribs.
25. Masonry, Carpentry. a wedge, as for tightening a joint or splitting a stone or timber.
26. Carpentry. a small piece of wood set into a timber across the grain to prevent warping.
27. Building Trades. any grooving or roughness applied to a surface to improve its bond with another surface.
28. Basketball. keyhole (  def 2 ) .
29. 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.
30. Painting. the tonal value and intensity of a color or range of colors: Rembrandt's colors are characterized by their low key.
31. Botany . a samara.
32. ( initial capital letter ) a member of the House of Keys.
33. keys, spiritual authority.

Adjective
34. chief; major; important; essential; fundamental; pivotal: a key person in the company; key industries.
verb (used with object), keyed, key·ing.
35. 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.
36. Music. to regulate the key or pitch of.
37. Painting.
a. to paint (a picture) in a given key.
b. to adjust the colors in (a painting) to a particular hue: He keyed the painting to brown.
38. to fasten, secure, or adjust with a key, wedge, or the like, as parts of a mechanism.
39. to provide with a key.
40. (in the layout of newspapers, magazines, etc.) to identify, through signs or symbols, the positions of illustrations or pieces of copy in a dummy.
41. to lock with or as if with a key.
42. Masonry. to provide (an arch or vault) with a keystone.
43. Computers. keyboard (  def 4 ) .

Verb (used without object), keyed, key·ing.
44. to use a key.
45. Computers. keyboard (  def 4 ) .

Verb Phrases:
46. key in, Computers. keyboard (  def 4 ) .
47. key on,
a. Football. to watch the position and movements of an opponent in order to anticipate a play: The defensive backs keyed on the star receiver.
b. 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.
48. key up,
a. to bring to a particular degree of intensity of feeling, excitement, energy, nervousness, agitation, etc.: keyed up over the impending test.
b. to raise (a piece of masonry) by the insertion of a wedge or wedges.
c. to raise (the haunches of an arch) by the insertion of a voussoir.

Idioms:
49. power of the keys, the authority of a pope in ecclesiastical matters, vested in him as successor of St. Peter.

Origin:
before 900; Middle English key ( e ), kay ( e ), Old English cǣg, cǣge;  cognate with Old Frisian kei, kai

Synonyms
6. answer, explanation, resolution, clue.

Example Sentences:
With an iron key , he unlocks the door to a storage room.
Learn about key  events in history and their connections to today.
Most of the time is spent moving the fingers in the air towards the next key .
The key  ingredient of the superglue that mussels use to attach themselves to   rocks, boats and piers is iron, scientists say.
The key  to the puzzle, they found, is that limestone erodes relatively easily.
The key  to successful grilling is starting with a tasty cut of meat.
In a shared key  system, you give one key  to your friends while you retain a private copy on your machine.
Please note that only applications which address the key  selection criteria will be considered.
In principle, the technique provides the makings of an unbreakable cryptographic key .
The key  ingredient is limestone, mostly calcium carbonate, the remains of shelled marine creatures.