noun
Have you lost your car keys again? You will need a key to open the air valve on the radiator
The key to his behaviour can probably be found in the way his mother treated him in his childhood
The song was originally written in the key of C
A key to the symbols appears on every other page
In this passage there is a change to a more sombre key
adjective
Automatic reversal is a key feature of this cassette player. Roderick is a key man in the company
US