key

Webster's Dictionary (1913)

Origin: OE. keye, key, kay, AS. cæg.

1. 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.

2. A small device which is inserted into a mechanism and turned like a key to fasten, adjust, or wind it; as, a watch key; a bed key; the winding key for a clock, etc.

3. One of a set of small movable parts on an instrument or machine which, by being depressed, serves as the means of operating it; the complete set of keys is usually called the keyboard; as, the keys of a piano, an organ, an accordion, a computer keyboard, or of a typewriter. The keys may operate parts of the instrument by a mechanical action, as on a piano, or by closing an electrical circuit, as on a computer keyboard. See also senses 12 and 13.

4. A position or condition which affords entrance, control, pr possession, etc.; as, the key of a line of defense; the key of a country; the key of a political situation. Hence, that which serves to unlock, open, discover, or solve something unknown or difficult; as, the key to a riddle; the key to a problem. Similarly, see also senses 14 and 15.

Those who are accustomed to reason have got the true key of books.— John Locke

Who keeps the keys of all the creeds.— Alfred Tennyson

5. That part of a mechanism which serves to lock up, make fast, or adjust to position.

6. Architecture (a) A piece of wood used as a wedge. (b) The last board of a floor when laid down.

7. Masonry (a) A keystone. (b) That part of the plastering which is forced through between the laths and holds the rest in place.

8. Machinery (a) A wedge to unite two or more pieces, or adjust their relative position; a cotter; a forelock. See Illusts. of Cotter, and Gib. (b) 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.

9. Botany An indehiscent, one-seeded fruit furnished with a wing, as the fruit of the ash and maple; a samara; — called also key fruit.

10. Music (a) 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. (b) The fundamental tone of a movement to which its modulations are referred, and with which it generally begins and ends; keynote.

Both warbling of one song, both in one key.— William Shakespeare

11. Fig: The general pitch or tone of a sentence or utterance.

You fall at once into a lower key.— William Cowper

12. Telegraphy 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; as, a telegraph key.

13. any device for closing or opening an electric circuit, especially as part of a keyboard, as that used at a computer terminal or teletype terminal.

14. 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 Biology a table or synopsis of conspicuous distinguishing characters of members of a taxonomic group.

15. Computers A word or other combination of symbols which serves as an index identifying and pointing to a particular record, file, or location which can be retrieved and displayed by a computer program; as, a database using multi-word keys. When the key is a word, it is also called a keyword.

Key bed. Same as Key seat. — Key bolt, a bolt which has a mortise near the end, and is secured by a cotter or wedge instead of a nut. Key bugle. See Kent bugle. — Key of a position or Key of a country. Military See Key, 4. — Key seat Machinery, a bed or groove to receive a key which prevents one part from turning on the other. — Key way, a channel for a key, in the hole of a piece which is keyed to a shaft; an internal key seat; — called also key seat. — Key wrench Machinery, an adjustable wrench in which the movable jaw is made fast by a key. — Power of the keys Church, the authority claimed by the ministry in some Christian churches to administer the discipline of the church, and to grant or withhold its privileges; — so called from the declaration of Christ, “I will give unto thee the keys of the kingdom of heaven.” Matt. xvi. 19.

1. To fasten or secure firmly; to fasten or tighten with keys or wedges. Philip Francis

2. Computers To enter (text, data) using keys, especially those on a keyboard; to keyboard; as, to key the data in by hand.

3. To adjust so as to be maximally effective in a particular situation; — of actions, plans, or speech; as, to key one's campaign speech to each local audience.

4. To furnish with a key or keys.

To key up. (a) Architecture To raise (the whole ring of an arch) off its centering, by driving in the keystone forcibly. (b) Music To raise the pitch of. (c) Hence, fig., to produce nervous tension in; as, the whole team was keyed up for the championship game.

Essential; most important; as, the key fact in the inquiry; the president was the key player in the negotiations.

Webster’s Revised Unabridged Dictionary (1913), from GCIDE 0.54 · with additions: +PJC, 1913 supplement, GCIDE editors

Free On-line Dictionary of Computing

1.<database> A value used to identify a record in a database, derived by applying some fixed function to the record. The key is often simply one of the fields (a column if the database is considered as a table with records being rows, see "key field"). Alternatively the key may be obtained by applying some function, e.g. a hash function, to one or more of the fields. The set of keys for all records forms an index. Multiple indexes may be built for one database depending on how it is to be searched.

2.<cryptography> A value which must be fed into the algorithm used to decode an encrypted message in order to reproduce the original plain text. Some encryption schemes use the same (secret) key to encrypt and decrypt a message, but public key encryption uses a "private" (secret) key and a "public" key which is known by all parties.

3.<hardware> An electromechanical keyboard button.

(2003-07-04)