n. 1 latchkey, skeleton key, passkey, opener Have you lost your car keys again? You will need a key to open the air valve on the radiator 2 clue, cue, guide, indication, indicator, explanation The key to his behaviour can probably be found in the way his mother treated him in his childhood 3 pitch, tone, timbre, level, tonality, frequency The song was originally written in the key of C 4 legend, explanation, description, explication, clarification, translation A key to the symbols appears on every other page 5 mood, tenor, tone, humour, style In this passage there is a change to a more sombre key
adj. 6 important, essential, vital, necessary, crucial, critical, main, pivotal Automatic reversal is a key feature of this cassette player Roderick is a key man in the company.