Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

English definition of “key”

See all translations

key

noun [C] uk   /kiː/ us  

key noun [C] (LOCK)

A1 a piece of metal that has been cut into a special shape and is used for opening or closing a lock, starting a car engine, etc.: car/door keys
More examples

key noun [C] (PART)

B2 any of the set of moving parts that you press with your fingers on a computer keyboard, or musical instrument to produce letters, numbers, symbols, or musical notes
More examples

key noun [C] (MUSICAL NOTES)

a set of musical notes based on one particular note: The song changes key halfway through. the key of C minor

key noun [C] (SYMBOLS)

a list of the symbols used in a map or book with explanations of what they mean

key noun [C] (ANSWERS)

A2 a list of the answers to the questions in an exercise or test: See the key to test 3 on page 176.

key

adjective uk   /kiː/ us  
B2 very important and having a lot of influence on other people or things: She was a key figure in the international art world. a key factor in tackling the problem
More examples
(Definition of key from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
What is the pronunciation of key?
Add Cambridge dictionaries to your browser to your website

Definitions of “key” in other dictionaries

Word of the Day

comma

the symbol , used in writing to separate parts of a sentence showing a slight pause, or to separate the single things in a list

Word of the Day

Lies, lies, lies!

by Kate Woodford,
February 25, 2015
​​​ According to sociologists (=people who study the relationships between people living in groups), we are good at lying. As a species, we have developed a remarkable ability to deceive each other (= persuade each other that something false is true). Being able to say things that are not true can help with

Read More 

snapchat verb

March 02, 2015
to send someone a message using the photomessaging application Snapchat We used to have a thing until he got a girlfriend. now

Read More