key

plural keys

1. countableAn object designed to open and close a lock or to activate or deactivate something, especially a length of metal inserted into a narrow opening on the lock to which it is matched (keyed).

   This key is to the backdoor.

   3 more examples

   insert the key into the lock (formal); put the key in the lock (informal)

   apartment key; room key; spare key

   We tiptoed into the house, up the stairs and along the hall to the door of 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[rosby] Lincoln, chapter XIII, in Mr. Pratt’s Patients, New York, N.Y.; London: D[aniel] Appleton and Company, →OCLC, pages 304–305

   1. countableA card or fob that electronically signals a lock to open.

      My hotel room key is a card.

      1 more example

      The gym will give you a fob that opens the door.

      Synonyms: key fob, keycard

   2. countablefigurativelycomputingA piece of information (e.g., a password or passphrase) used to encode or decode a message or messages.
   3. InternetcountableA 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)

   4. countableslangA key bump (A portion of a recreational drug in powdered form that is snorted from a key or similar small object.)

      I saw him snort a key at the party.

   5. countableAny of various tools comparable to a wrench (spanner) or driver, which have a specialized end that matches a fixture, analogously to a lock's key.

      Safe-deposit boxes open with a special key.

      1 more example

      The exterminator will bring a key thingy that can open the bait boxes.

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.
   1. machineryA cotter pin.
   2. architectureA piece of wood used as a wedge.
   3. architectureThe last board of a floor when laid down.
   4. businessA keystone.
   5. That part of the plastering which is forced through between the laths and that holds the rest in place.
   6. rail transportA wooden wedge, driven sideways between a bullhead rail and a cast-iron chair, to keep the rail securely in position.
3. figurativelyA crucial step or requirement.

   Persistence is the key to solving this problem.

   5 more examples

   The key to winning that game is your strategy at the beginning.

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

   a. 1705, John Locke, “Of the Conduct of the Understanding”, in Posthumous Works of Mr. John Locke: […], London: […] A[wnsham] and J[ohn] Churchill, […], published 1706, →OCLC

   who keeps the keys of all the creeds

   1850, [Alfred, Lord Tennyson], “(please specify |part=Prologue or Epilogue, or |canto=I to CXXIX)”, in In Memoriam, London: Edward Moxon, […], →OCLC

   The PEOPLE'S DAILY today front pages a news item in column one in the experience of Yuhsi County in Yunnan which "mastered the law of agricultural field management, and found the key to increasing autumn grain production."

   1960 August 29 [1960 August 26], “Higher Autum Grain Yield is Possible”, in Daily Report: Foreign Radio Broadcasts, number 168, Foreign Broadcast Information Service, sourced from Peking NCNA, translation of original in Chinese, →OCLC, Communist China: National Affairs, page BBB 2-BBB 3

   Imagination is the key to creation. Whatever you can imagine becomes reality or is reality. That's the way it works.

   2015, Omnec Onec, Simply Wisdom and Love

   1. broadlyfigurativelyAn idea, theory or observation that explains, justifies or renders (something) comprehensible.

      The key to his proposal is that he thinks this company is dying and needs radical change.

   2. figurativelyA deciding factor.

      Her charm is the key to her success.

4. Senses relating to a guide that identifies information.
   1. A small guide explaining symbols, abbreviations or terminology, especially the legend on a map or chart.

      map key

      1 more example

      The key says that A stands for the accounting department.

   2. A guide to the correct answers of a worksheet or test.

      Some students cheated by using the key.

      Synonyms: answer key

   3. biologyA series of logically organized groups of discriminating information which aims to allow the user to correctly identify a taxon; a taxonomic key.
   4. computingA value that uniquely identifies an entry in a container.
   5. computingIn a relational database, a field used as an index into another table (not necessarily unique).
5. Senses relating to a set of features that modify the output of a device.
   1. computingOne of several small, usually square buttons on a typewriter or computer keyboard, mostly corresponding to text characters.

      A key; B key, etc.

      1 more example

      Press the Escape key.

   2. entertainmentIn musical instruments, one of the valve levers used to select notes, such as a lever opening a hole on a woodwind.

      piano key

   3. 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.
6. entertainmentA scale or group of pitches constituting the basis of a musical composition.

   the key of B-flat major

   1 more example

   A girl, it is true, has always lived in a glass house among reproving relatives, whose word was law; she has been bred up to sacrifice her judgments and take the key submissively from dear papa; and it is wonderful how swiftly she can change her tune into the husband's.

   1881, R.L. Stevenson, Virginibus Puerisque

   1. entertainmentThe lowest note of a scale; keynote.
   2. entertainmentIn musical theory, the total melodic and harmonic relations, which exist between the tones of an ideal scale, major or minor; tonality.
   3. entertainmentIn 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. entertainmentIn musical notation, a sign at the head of a staff indicating the musical key.
   5. figurativelyentertainmentThe general pitch or tone of a sentence or utterance.

      ?, William Cowper, Conversation You fall at once into a lower key.

      2 more examples

      2. Queen.[…]Deere Glasse of Ladies Bid him that we whom flaming war doth scortch, Vnder the shaddow of his Sword, may coole us: Require him he advance it ore our heades; Speak't in a womans key: like such a woman As any of us three; weepe ere you faile; lend us a knee; But touch the ground for us no longer time Then a Doves motion, when the head's pluckt off: Tell him if he i'th blood cizd field, lay swolne Showing the Sun his Teeth; grinning at the Moone What you would doe.

      1613–1614 (date written), John Fletcher, William Shak[e]speare, The Two Noble Kinsmen: […], London: […] Tho[mas] Cotes, for Iohn Waterson; […], published 1634, →OCLC, Act I, scene i, page 1

      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

   6. broadlyfigurativelyadvertisingA modification of an advertisement so as to target a particular group or demographic.
7. Senses of items with visual similarity to a key or group of keys on a keyring.
   1. An item of decor shaped like a key.
   2. biologyAn indehiscent, one-seeded fruit furnished with a wing, such as the fruit of the ash and maple; a samara.

      Synonyms: key-fruit

   3. ball gamesThe 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.

   4. cartomancyThe thirty-third card of the Lenormand deck, which features an image of a key.
8. Senses related to colors.
   1. artThe overall color tone of a painting or other visual art, with a high key indicating generally light colors and a low key indicating generally dark colors.
   2. print and filmThe black ink layer, especially in relation to the three color layers of cyan, magenta, and yellow. See also CMYK.
   3. broadcastingA 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

      1 more example

      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

9. historicalA manual electrical switching device primarily used for the transmission of Morse code.
10. The degree of roughness, or the ability of a surface to retain an applied liquid, such as paint or glue.

    The door panel should be sanded down carefully to provide a good key for the new paint.

comparative keyer · comparative more key · superlative keyest · superlative most key

1. not comparableusuallyIndispensable, supremely important.

   He is the key player on his soccer team.

   4 more examples

   Paradoxically enough, however, in general only the parties of the Left have done most to spread the belief that it was the numerical strength of the opposing material interests which decided political issues, whereas in practice these same parties have regularly and successfully acted as if they understood the key position of the intellectuals.

   1949, F. A. Hayek, “The Intellectuals and Socialism”, in University of Chicago Law Review, volume 16, number 3, Chicago: University of Chicago, →DOI, page 418

   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).

   2014 October 14, 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., →ISBN, 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. not comparableusuallyImportant, salient.

   She makes several key points.

   2 more examples

   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.

   2011 September 29, Jon Smith, “Tottenham 3 - 1 Shamrock Rovers”, in BBC Sport

present singular third person keys · participle present keying · participle past keyed · past keyed

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.

   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: […]

   3 more examples

   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, →ISBN, 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, →ISBN, 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, →ISBN, page 12

4. broadcastingTo depress (a telegraph key).
5. broadcastingTo 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. colloquialTo 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).

   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

   2 more examples

   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

9. intransitivebiologyTo be identified as a certain taxon when using a key.
10. transitiveadvertisingTo 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

    1 more example

    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.

    To Ethel alone she addressed a stray remark, keyed below the sound of other voices.

    1930, Norman Lindsay, Redheap, Sydney, N.S.W.: Ure Smith, →OCLC, page 23

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).
14. To provide an arch with a keystone.

    The last arch in the permanant ^([sic]) bridge was keyed on March 26, 1850, and a single track was brought into use for goods trains on July 20.

    1950 September, “Centenary of the Royal Border Bridge”, in Railway Magazine, page 637

15. abbreviationclippingClipping of chromakey.

    After keying the background, you’d be left with a transparent background, where you can install anything—from images to videos that blend seamlessly into the main subject of the shot.

    2021 September 11, Anina Ot, “What Is a Green Screen and How Does It Work?”, in MakeUseOf

plural keys · alternative cay

1. One of a string of small islands.

   the Florida Keys

plural keys · alternative ki · alternative keye · alternative kee

1. slangA 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

   Synonyms: kay

plural keys

1. alternativeAlternative form of quay.

plural keys

1. Australian rules footballA key position player (a tall forward or defender).

   "It just means that one of them here and there will need to play on a small-to-medium forward (instead of Riewoldt) which is fine. Our keys are pretty agile."

   2023 April 7, “'Bit of a surprise': Dogs bemused by Tigers' selection call”, in Australian Football League, retrieved 27 Jul 2025

plural Keys

1. A surname.