# key

Pronunciation: say "KEE" US /ki/, UK /kiː/

## Noun

1. An object used to open and close a lock, usually a shaped piece of metal but also an electronic card or fob.
   - Simple: A small metal object, or a card, used to open or close a lock.
   - _The locksmith cut a new key for the front door._
   - _Each key on the ring opened a different office._
3. Something that is crucial for achieving a result, or that explains or solves a problem or mystery.
   - Simple: The one thing you most need to make something happen, or to understand or solve something.
   - _Clear communication is the key to a successful project._
   - _Discipline became the key to her steady improvement._
4. One of the small, usually square buttons on a typewriter or computer, most of them standing for text characters.
   - Simple: One of the small buttons you press to type letters or numbers.
   - _He hit the return key to start a new line._
   - _Several keys on the old typewriter were stuck._
5. A piece of information, such as a password, used to encode or decode messages.
   - Simple: A piece of information used to turn a message into code or change it back into readable form.
   - _The two agents shared a key for decoding their messages._
   - _Anyone who steals the key can read every encrypted file._
6. A scale or group of pitches that forms the basis of a piece of music.
   - Simple: The group of musical notes that a song is built on.
   - _The symphony shifts to a minor key in its second movement._
   - _She transposed the song into a higher key for her voice._
7. On a musical instrument such as a piano, organ or woodwind, one of the levers or buttons pressed to sound or select a particular note.
   - Simple: One of the parts you press on a piano or other instrument to play a note.
   - _He ran his fingers across the keys in a quick scale._
   - _One ivory key on the old organ no longer made any sound._
9. A code used to activate or unlock software, a game, or an online service, or to get access to it; a license key is one kind.
   - Simple: A code of letters and numbers that lets you start using a program, game, or online service.
   - _The download is free, but you need a key to activate the full version._
   - _Reviewers received early keys a week before the game's release._
10. The answer sheet used to mark a worksheet or test, giving the correct response for each item.
   - Simple: A list of the correct answers to a test or worksheet.
   - _The grader marked each paper against the key._
   - _Students aren't allowed to see the key during the exam._
11. A brief guide to the meanings of symbols or terms, especially those used on maps and charts.
   - Simple: A small guide that explains the symbols on a map or chart.
   - _The chart's key explained each symbol in the diagram._
   - _She checked the key to identify the shaded regions on the map._
8. A small, low island, usually of sand or coral, as in the Florida Keys.
   - Simple: A small, low island made of sand or coral.
   - _The boat anchored beside a sandy key just off the reef._
   - _A chain of keys stretched south from the mainland._
12. In computing, a value or field used to identify or look up an entry in a collection of data, such as a record in a database table.
   - Simple: In computing, a value used to find or label a piece of stored data.
   - _The dictionary stores each value under a unique key._
   - _Looking up a record by its key returns the matching entry._
15. The prevailing tone or emotional pitch of something said or written.
   - Simple: The overall tone or mood in the way something is said.
   - _The whole letter was pitched in a hopeful key._
   - _After two grim chapters, the memoir shifts into a lighter, more comic key as the family moves to the coast._
16. In biology, a logically arranged set of distinguishing features, grouped in stages, that lets a user correctly identify a species or other taxon.
   - Simple: A set of steps or questions that helps you find out what kind of plant or animal something is.
   - _One step in the key asks whether the leaves grow opposite or alternate on the stem._
   - _The field guide's keys to wildflowers start with petal number and color._
17. Any of various tools similar to a wrench or driver, and in some cases also called a wrench or driver.
   - Simple: A small tool used to turn, tighten, or wind something, similar to a wrench or screwdriver.
   - _The technician fitted a hex key into the recessed bolt._
   - _Tuning the drum kit, he reached for the key that tightens each lug._
18. In basketball, the free-throw lane together with the circle around the free-throw line, an area shaped roughly like a keyhole.
   - Simple: In basketball, the painted area near the basket where players stand for free throws.
   - _The point guard drove into the key and kicked the ball out to a shooter._
   - _She pulled up just outside the key for a mid-range jumper._
19. A quantity weighing one kilogram, used particularly when the substance is a recreational drug. *(slang)*
   - Simple: A kilogram, usually of an illegal drug.
   - _Smugglers moved several keys across the border each week._
   - _He bragged about flipping a key for double what he paid._
20. A part designed to fit between two components, such as a shaft and a wheel, to keep them aligned and turning together.
   - Simple: A small part that fits between two pieces of a machine to hold them in the same position.
   - _The technician seated a steel key in the slot before mounting the flywheel._
   - _If the key shears, the coupling spins freely and the drive fails._
25. The central wedge-shaped stone at the crown of an arch that locks the surrounding stones in place; a keystone.
   - Simple: The wedge-shaped stone at the top of an arch that holds the other stones in place.
   - _Removing the key would bring the entire arch crashing down._
   - _Each arched window of the old courthouse had a carved stone key at its crown._
26. A hand-operated electrical switch used mainly to send messages in Morse code.
   - Simple: A hand-operated switch used to tap out messages in Morse code.
   - _The radioman worked the key nonstop as the storm worsened._
   - _An old straight key sat on the desk beside the receiver._
27. A dry, one-seeded fruit with a wing that helps it spin and drift on the wind, such as the fruit of the ash and maple; a samara.
   - Simple: A dry, winged fruit with a single seed, like the spinning fruit of a maple tree.
   - _A single key drifted down from the sycamore and landed on the path._
   - _The breeze sent maple keys twirling across the lawn._
28. How rough a surface is, or how well it grips a liquid such as paint or glue spread over it.
   - Simple: The roughness of a surface that helps paint or glue stick to it.
   - _A light pass with fine sandpaper dulls the old varnish and gives the primer a key to grip._
   - _Glossy plastic offers a poor key for most adhesives, so roughen it before gluing._

## Adjective

2. Important and standing out as significant.
   - Simple: Very important, or the most important.
   - _The witness shared a key detail that changed the case._
   - _Location is a key consideration when buying a home._

## Verb

13. To enter information by typing it on a keyboard or keypad.
   - Simple: To type information into a computer or keypad.
   - _The clerk keyed each total into the register._
   - _You key the code into the panel to unlock the door._
14. To deliberately scratch and damage a car or similar object with a key or sharp tool. *(colloquial)*
   - Simple: To scratch and damage a car on purpose using a key.
   - _Vandals keyed every car parked along the street._
   - _He threatened to key her car after the argument._
21. To fit the parts of a mechanical assembly together with a key so they keep the same orientation.
   - Simple: To join parts of a machine with a key so they stay lined up.
   - _Assemblers key the coupling halves to prevent any rotation between them._
   - _The fitter keyed the pulley to the drive shaft before tightening the set screw._
22. To fit a lock with a key so that the matching key operates it.
   - Simple: To set up a lock so a particular key works in it.
   - _They key every apartment door so a single master opens them all._
   - _The shop keyed the office locks alike for the new tenant._
23. To attune or set something to a particular pitch, level, or tone.
   - Simple: To set something to match a certain mood, level, or pitch.
   - _The film's composer keyed the music to the quiet sadness of each scene._
   - _Skilled hosts key the conversation to whatever the room needs._
24. To mark, code or link items so that they match the symbols or categories in a key or legend.
   - Simple: To label or link things so they match the groups or symbols in a key.
   - _She keyed the survey responses to the demographic categories._
   - _Teachers key the practice questions to the day's lesson goals._

## Other meanings

- (noun) In printing, the black ink layer, used together with the cyan, magenta, and yellow layers.
- (noun) The first and lowest note of a musical scale, on which the scale is built.
- (noun) In music theory, the whole system of relationships among the notes of a major or minor scale, as heard in melody and harmony.
- (noun) In written music, the group of sharps or flats at the start of a staff that shows which key a piece is in.
- (noun) A small change made to an advertisement, such as a code in its reply address, so that it aims at or tracks one group of customers.
- (noun) On IRC chat networks, a password that must be entered to join a protected channel.
- (noun) A wooden wedge driven in to hold something tight.
- (noun) The final floorboard put in place when a floor is being laid.
- (noun) The plaster that squeezes through the gaps between laths and hardens there, anchoring the outer coat.
- (noun) On older railway track, a wooden wedge hammered in beside the rail to hold it firmly in its iron chair.
- (noun) In Lenormand fortune-telling cards, card number 33 of the deck.
- (noun) In video and image editing, a chosen color that is removed or made see-through so another picture can show behind it.
- (noun) In Australian rules football, a tall player who plays in one of the main forward or defensive positions.
- (verb) To send a signal by pushing down on a telegraph key.
- (verb) To press down the push-to-talk button so a two-way radio begins sending.
- (verb) Of a living thing, to turn out to be a particular species or group when checked against an identification key.
- (verb) To alter an ad slightly so it reaches, or can be traced back to, one chosen set of people.
- (verb) To make something tight or secure, especially by driving in wedges or keys.
- (verb) To get a wall ready for plastering by giving the first coat something to grip, such as gaps between laths.
- (verb) To set the central locking stone into the top of an arch.
- (verb) To combine video images using chroma key, removing one color so another picture shows through.
- (noun) An older spelling of quay, a place where ships load and unload.

## Origin

**Meanings 1–7, 9–18, 20–28** — From Middle English keye, from Old English cǣġ ("key, solution"), of uncertain origin. Its only sure cognates are in Frisian, and it may come from Proto-Germanic *kēgaz ("stake, post, pole"), reflecting how early keys could be long hooked poles used to lift a bar off a door from outside.
**Meaning 8** — Spanish "cayo" is the source of this word, which is another spelling of "cay". Spanish had taken it from the Taíno word "cayo", meaning a small island.
**Meaning 19** — A clipping of kilogram or kilo.

Source: DictionaryAI, https://dictionaryai.com/define/key (written from Wiktionary data, CC BY-SA 4.0: https://creativecommons.org/licenses/by-sa/4.0/).