important nounthe part of a computer or typewriter which you press with your fingers ExampleThere are sixty-four keys on the keyboard.adjectiveimportant Examplesa key factor • key industries • key personnel • a key member of our management team • She has a key post in the organisation. • We don't want to lose any key staff in the reorganisation."...he gave up the finance job in September to devote more time to his global responsibilities as chairman and to work more closely with key clients" [Times] the part of a computer or typewriter which you press with your fingers