key

Etymology 1

From Middle English keye, kaye, keiȝe, from Old English cǣġ (“key, solution, experiment”) (whence also Scots key and kay (“key”)), of uncertain origin. The only sure cognates are Saterland Frisian Koai (“key”), West Frisian kaai (“key”), and North Frisian kay (“key”). Possibly from Proto-Germanic *kēgaz, *kēguz (“stake, post, pole”), from Proto-Indo-European *ǵogʰ-, *ǵegʰ-, *ǵegʰn- (“branch, stake, bush”), which would make it cognate with Middle Low German kāk (“whipping post, pillory”), and perhaps to Middle Dutch keige (“javelin, spear”) and Middle Low German keie, keige (“spear”). For the semantic development, note that medieval keys were simply long poles (ending in a hook) with which a crossbar obstructing a door from the inside could be removed from the outside, by lifting it through a hole in the door. Liberman has noted, however, "The original meaning of *kaig-jo- was presumably '*pin with a twisted end.' Words with the root *kai- followed by a consonant meaning 'crooked, bent; twisted' are common only in the North Germanic languages."

noun

1. An object designed to open and close a lock.
   We tiptoed into the house, up the stairs and along the hall into the room where the Professor had been spending so much of his time. 'Twas locked, of course, but the Deacon man got a big bunch of keys out of his pocket and commenced to putter with the lock. 1913, Joseph C. Lincoln, chapter 13, in Mr. Pratt's Patients
2. An object designed to fit between two other objects (such as a shaft and a wheel) in a mechanism and maintain their relative orientation.
3. A crucial step or requirement.
   The key to solving this problem is persistence.
   the key to winning a game
4. A guide explaining the symbols or terminology of a map or chart; a legend.
   The key says that A stands for the accounting department.
5. A guide to the correct answers of a worksheet or test.
   Some students cheated by using the answer key.
6. (computing) One of several small, usually square buttons on a typewriter or computer keyboard, mostly corresponding to text characters.
   Press the Escape key.
7. (music)
   1. In musical instruments, one of the valve levers used to select notes, such as a lever opening a hole on a woodwind.
   2. In instruments with a keyboard such as an organ or piano, one of the levers, or especially the exposed front end of it, which are depressed to cause a particular sound or note to be produced.
8. (music) A scale or group of pitches constituting the basis of a musical composition.
   1. The lowest note of a scale; keynote.
   2. In musical theory, the total melodic and harmonic relations, which exist between the tones of an ideal scale, major or minor; tonality.
   3. In musical theory and notation, the tonality centering in a given tone, or the several tones taken collectively, of a given scale, major or minor.
   4. In musical notation, a sign at the head of a staff indicating the musical key.
9. (figurative) The general pitch or tone of a sentence or utterance.
   ?, William Cowper, Conversation You fall at once into a lower key.
10. (advertising) A modification of an advertisement so as to target a particular group or demographic.
    Another popular way to key ads and mailings is to use a suite number, room number, department number, desk number, etc. as part of the ordering address. With a classified ad, using such a key may increase your ad cost. 1998, Mail Order Success Secrets
11. (botany) An indehiscent, one-seeded fruit furnished with a wing, such as the fruit of the ash and maple; a samara.
12. (historical) A manual electrical switching device primarily used for the transmission of Morse code.
13. (cryptography) A piece of information (e.g., a password or passphrase) used to encode or decode a message or messages.
14. (Internet) A password restricting access to an IRC channel.
    if you know someone who is in the channel, you can query them and ask for the key. 2000, Robert Erdec, “Re: Help; mIRC32; unable to resolve server arnes.si”, in alt.irc.mirc (Usenet)
15. (databases) In a relational database, a field used as an index into another table (not necessarily unique).
16. (computing) A value that uniquely identifies an entry in a container.
17. (basketball) The free-throw lane together with the circle surrounding the free-throw line, the free-throw lane having formerly been narrower, giving the area the shape of a skeleton key hole.
    He shoots from the top of the key.
18. (biology) A series of logically organized groups of discriminating information which aims to allow the user to correctly identify a taxon.
19. (architecture) A piece of wood used as a wedge.
20. (architecture) The last board of a floor when laid down.
21. (masonry) A keystone.
22. That part of the plastering which is forced through between the laths and holds the rest in place.
23. (rail transport) A wooden support for a rail on the bullhead rail system.
24. The degree of roughness, or retention ability of a surface to have applied a liquid such as paint, or glue.
    The door panel should be sanded down carefully to provide a good key for the new paint.
25. (cartomancy) The thirty-third card of the Lenormand deck.
26. (print and film) The black ink layer, especially in relation to the three color layers of cyan, magenta, and yellow. See also CMYK.
27. (computer graphics, television) A color to be masked or made transparent.
    You can easily create this type of user interface by creating a bitmap with certain portions set to a predefined color you want to use as the transparency key. 2004, Mark Schmidt, Simon Robinson, Microsoft Visual C# .NET 2003 Developer's Cookbook, page 195
    There are key controls that adjust the “slice level” or the level at which the key kicks-in and starts cutting a hole for the “fill” […] Chroma key is another form of keying, which derives the key cutter or hole from a selected color. 2016, Jerry C. Whitaker, The SBE Broadcast Engineering Handbook

adj

1. Indispensable, supremely important.
   He is the key player on his soccer team.
   Lukas intimates that one of Disney's key attractions was "Main Street USA,” which "mimicked a downtown business district just as Southdale" had done. 2007, Mark H. Moss, Shopping as an Entertainment Experience, page 46
   The question of the plausibility of the counter-factual is seen as key in all three discussions of allohistorical fiction (as it is in Demandt's and Ferguson's examinations of allohistory) (cf. Rodiek 25–26; Ritter 15–16; Helbig 32). 14 October 2014, David Malcolm, “The Great War Re-Remembered: Allohistory and Allohistorical Fiction”, in Martin Löschnigg, Marzena Sokolowska-Paryz, editors, The Great War in Post-Memory Literature and Film, Walter de Gruyter GmbH & Co KG., page 173
   The enemy is moving troops through a key area. Distrupt their activities to open some holes in their defenses. 2017, BioWare, Mass Effect: Andromeda (Science Fiction), Redwood City: Electronic Arts, →OCLC, PC, scene: Disrupt Enemy Movements
2. Important, salient.
   She makes several key points.
   Throughout the 1500s, the populace roiled over a constellation of grievances of which the forest emerged as a key focal point. The popular late Middle Ages fictional character Robin Hood, dressed in green to symbolize the forest, dodged fines for forest offenses and stole from the rich to give to the poor. But his appeal was painfully real and embodied the struggle over wood. 2006, Edwin Black, chapter 2, in Internal Combustion
   With the north London derby to come at the weekend, Spurs boss Harry Redknapp opted to rest many of his key players, although he brought back Aaron Lennon after a month out through injury. September 29, 2011, Jon Smith, “Tottenham 3 - 1 Shamrock Rovers”, in BBC Sport

verb

1. To fit (a lock) with a key.
2. To fit (pieces of a mechanical assembly) with a key to maintain the orientation between them.
3. To mark or indicate with a symbol indicating membership in a class.
   So I worked on a tissue-paper copy of the perimeter plan, outlining groupings of plants of the same species and keying them with letters for the species. 1996 January, Garden Dsign Ideas, second printing, Taunton Press, page 25
   The volume closes with thirty pages of "Notes, critical and explanatory," in which Thomson provides seventy-six longer or shorter notes keyed to specific sections of the synopsis. 2001, Bruce M. Metzger, The Bible in Translation, page 87
   Talk about similarities between the words and write them below to the left of the anchor, keying them with a plus sign (+). Talk about the characteristics that set the words apart and list them below the box to the right, keying them with a tilde sign (~). 2002, Karen Bromley, Stretching Students' Vocabulary, page 12
   2007, Stephen Blake Mettee, Michelle Doland, and Doris Hall, compilers, The American Directory of Writer's Guidelines, 6th ("2007–2008") edition, →ISBN, page 757, Indicate the comparative value of each heading by keying it with a number in pencil, in the left margin, as follows: […]
4. (telegraphy and radio telegraphy) To depress (a telegraph key).
5. (radio) To operate (the transmitter switch of a two-way radio).
6. (computing) (more usually to key in) To enter (information) by typing on a keyboard or keypad.
   Our instructor told us to key in our user IDs.
7. (colloquial) To vandalize (a car, etc.) by scratching with an implement such as a key.
   He keyed the car that had taken his parking spot.
8. To link (as one might do with a key or legend).
   The American Heart Association has prepared their own guide to classification and, keying it with the Standard Nomenclature of Diseases, have done much to encourage a concise yet complete diagnosis. 1960, Richard L. Masland, “Classification of the Epilepsies”, in Epilepsia, volume 1, page 516
   The workman's compensation system rests on incentives (premium payments) that are keyed to the immediate and relatively undeniable nature of injuries; […] 1976, Nicholas Askounes Ashford, Crisis in the Workplace: Occupational Disease and Injury, page 19
   It also features special issues on "Live Longer, Better, Wiser," men's health, women's health, and issues keyed to important "disease weeks." 2006, Deborah Blum, Mary Knudson, Robin Marantz Henig, A Field Guide for Science Writers: The Official Guide of the National Association of Science Writers, page 63
9. (intransitive, biology, chiefly taxonomy) To be identified as a certain taxon when using a key.
10. (advertising, transitive) To modify (an advertisement) so as to target a particular group or demographic.
    Keying advertisements and counting the number of inquiries received or the number of coupons returned to indicate the "pulling power" of a particular piece of copy or the coverage of a particular advertising medium. 1936, John Freeman Pyle, Marketing Principles, Organization and Policies, page 711
    Another popular way to key ads and mailings is to use a suite number, room number, department number, desk number, etc. as part of the ordering address. With a classified ad, using such a key may increase your ad cost. Why? Because you're using an extra word or two to key the ad. 1998, Mail Order Success Secrets
11. To attune to; to set at; to pitch.
12. To fasten or secure firmly; to fasten or tighten with keys or wedges.
    they Mouldered and keyed the Portico Arches with Pieces of Stone, because Brick was not strong enough 1744, Roger North, The Life of the Honourable Sir Dudley North
13. To prepare for plastering by adding the key (that part of the plastering which is forced through between the laths and holds the rest in place).

Etymology 2

Variant of cay, from Spanish cayo, from Taíno cayo (“small island”)

noun

1. One of a string of small islands.
   the Florida Keys

Etymology 3

noun

1. Alternative form of quay.

Etymology 4

Abbreviating kilogram, via kilo.

noun

1. (slang) Clipping of kilogram (especially of a recreational drug)
   So starting with ten keys of cocaine and two keys of heroin, Derrick put his plan in motion. Soon every major drug dealer and gang chief from Chicago Avenue to Evanston was in his pocket. 2010, David J. Silas, Da Block, page 41