key

Meanings

1. 1nouncountable

   A small shaped piece of metal used to open a lock, start a vehicle, or work a mechanism.

   Grammar: Countable: one key, two keys. Often used with 'to': the key to the door.

   Patterns

   • the key to something
   • a key for something
   • turn the key

   I can't find my car key anywhere.

   She turned the key in the lock and opened the door.

   He keeps a spare key under the mat.

2. 2adjectivebefore a noun

   Most important; essential for success or for understanding something.

   Grammar: Used before a noun: a key factor, the key issue. Not usually after a verb.

   Patterns

   • a key factor
   • a key role
   • key to something

   Trust is a key factor in any friendship.

   She played a key role in the project's success.

   The key question is whether we can afford it.

3. 3nouncountablemusic

   In music, a set of notes that a piece is based on, named by its main note.

   Grammar: Countable: in the key of C, change key.

   Patterns

   • in the key of something
   • change key

   The song is in the key of G major.

   She sang in a higher key than usual.

   He struggled to stay in key during the chorus.

4. 4nouncountablecomputingmusic

   A button on a keyboard or piano that you press to produce a sound or type a character.

   Grammar: Countable: press a key, hit the wrong key.

   Patterns

   • press a key
   • hit a key

   Press the Enter key to confirm.

   One of the keys on my keyboard is stuck.

   She ran her fingers over the piano keys.

5. 5nouncountable

   A list that explains the symbols or answers used in a map, test, or book.

   Grammar: Countable: see the key at the back of the book.

   Patterns

   • the key to a map
   • answer key

   The map has a key showing what each symbol means.

   Check your answers against the key at the back.

   The teacher lost the answer key.

6. 6nouncountable

   A low island, especially in the Caribbean, such as the Florida Keys.

   Grammar: Countable, often in place names: Key West.

   Patterns

   • the Florida Keys

   They spent a week sailing around the keys.

   Key West is the southernmost island in the chain.

Word forms

Common combinations

key factor

Cost was a key factor in our decision.

key role

She played a key role in the negotiations.

car key

He left his car key in the ignition.

in the key of

The piece is written in the key of D minor.

press a key

Press any key to continue.

Synonyms and how they differ

crucial

Crucial is a close synonym for the adjective sense, but it is slightly stronger and more formal than key.

essential

Essential means absolutely necessary; key means very important but not always absolutely necessary.

button

Button is a general word for a part you press; key is used for keyboards and pianos.

Opposites

Word family

keyboard noun

The set of keys on a computer or piano.

keyhole noun

The hole in a lock where you put the key.

keyless adjective

Without a key, as in a keyless entry system.

Commonly confused: key or quay?

Practice

Make it your own

Write a sentence using “key”, then check it and compare it with the examples above.

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