key

[1]	identify , discover , key out , distinguish , describe , name

[1]	latchkey , skeleton key , passkey , opener
[2]	clue , cue , guide , indication , indicator , explanation
[3]	pitch , tone , timbre , level , tonality , frequency
[4]	legend , tonality , explanation , description , explication , clarification , translation
[5]	mood , tenor , tone , humour , style
[6]	samara , key fruit
[7]	Francis Scott Key
[8]	cay , Florida key
[9]	paint
[10]	winder
[11]	keystone , headstone

adj.

[1]	important , essential , vital , necessary , crucial , critical , main , pivotal
[2]	cardinal , central , fundamental , primal