Key

How to spell key

3 letters · 1 syllable

How to pronounce key

What does key mean?

1. nounA small shaped piece of metal cut to operate a particular lock.
2. adjectiveOf central importance; crucial to a result or plan.
3. nounA system of related notes based on a particular starting pitch.
4. nounAn explanatory list of symbols or answers that unlocks how to read something.

Key in a sentence

• noun

  She turned the key in the front door and stepped inside.

• adjective

  Customer trust is a key factor in growing the business.

• noun

  The choir sang the whole piece in the key of D major.

• noun

  The map included a key explaining each coloured symbol.

• noun

  He kept a spare key for the car hidden in the garage.

• adjective

  The manager identified the key steps needed before the launch.

Where does key come from?

Language of origin: Germanic

This word descends from the Old English cæg, which already meant a metal instrument for working a lock, and earlier still a solver or opener of things. Its deeper roots are obscure, with no certain relatives outside the West Germanic languages, so scholars cannot confidently trace it any further back. Over the centuries the spelling drifted through forms such as 'kay' and 'keye' before settling on the modern 'key'. The figurative senses grew naturally from the literal object: because a key unlocks something hidden, the word came to mean anything that gives access or explanation, hence a map's key or the answer key to a test. The musical sense, a tonal system anchored on one note, and the adjective sense meaning crucial or central both extend this idea of the thing that unlocks the whole. Note the homophone trap with 'quay', a borrowing from French of Celtic origin, which sounds identical but means a landing place for boats.

How the word is built

• key (from Old English cæg, a key; a single unanalysable root word with no prefix or suffix)

Words that sound like key

They sound the same but mean different things, so the meaning decides which spelling to write.

• quay: A solid, paved structure built along the edge of water where boats and ships are moored, loaded, and unloaded.