Definition of key :
1. A bar or key, in a typewriter or typesetting machine, used for spacing between letters.
2. A bar, pin or wedge, to secure a crank, pulley, coupling, etc., upon a shaft, and prevent relative turning; sometimes holding by friction alone, but more frequently by its resistance to shearing, being usually embedded partly in the shaft and partly in the crank, pulley, etc.
3. A family of tones whose regular members are called diatonic tones, and named key tone ( or tonic) or one ( or eight), mediant or three, dominant or five, subdominant or four, submediant or six, supertonic or two, and subtonic or seven. Chromatic tones are temporary members of a key, under such names as " sharp four," " flat seven," etc. Scales and tunes of every variety are made from the tones of a key.
4. A keystone.
5. A metallic lever by which the circuit of the sending or transmitting part of a station equipment may be easily and rapidly opened and closed; any device for closing or opening an electric circuit.
6. A piece of wood used as a wedge.
7. A simplified version or analysis which accompanies something as a clue to its explanation, a book or table containing the solutions to problems, ciphers, allegories, or the like, or a table or synopsis of conspicuous distinguishing characters of members of a taxonomic group.
8. A wedge to unite two or more pieces, or adjust their relative position; a cotter; a forelock.
9. An indehiscent, one- seeded fruit furnished with a wing, as the fruit of the ash and maple; a samara; - called also key fruit.
10. An instrument by means of which the bolt of a lock is shot or drawn; usually, a removable metal instrument fitted to the mechanism of a particular lock and operated by turning in its place.
11. An instrument which is turned like a key in fastening or adjusting any mechanism; as, a watch key; a bed key, etc.
12. Fig: The general pitch or tone of a sentence or utterance.
13. That part of a mechanism which serves to lock up, make fast, or adjust to position.
14. That part of an instrument or machine which serves as the means of operating it; as, a telegraph key; the keys of a pianoforte, or of a typewriter.
15. That part of the plastering which is forced through between the laths and holds the rest in place.
16. The fundamental tone of a movement to which its modulations are referred, and with which it generally begins and ends; keynote.
17. The last board of a floor when laid down.
18. To fasten or secure firmly; to fasten or tighten with keys or wedges.
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focal (part of speech: adjective)
island (part of speech: noun)
indication (part of speech: noun)
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