'key' in a sentence

: serving as an essential component

: metal device shaped in such a way that when it is inserted into the appropriate lock the lock's mechanism can be rotated

: something crucial for explaining

: pitch of the voice

: any of 24 major or minor diatonic scales that provide the tonal framework for a piece of music

: a kilogram of a narcotic drug

: a winged often one-seed indehiscent fruit as of the ash or elm or maple

: a coral reef off the southern coast of Florida

: (basketball) a space (including the foul line) in front of the basket at each end of a basketball court; usually painted a different color from the rest of the court

: a list of answers to a test

: a list of words or phrases that explain symbols or abbreviations

: a generic term for any device whose possession entitles the holder to a means of access

: mechanical device used to wind another device that is driven by a spring (as a clock)

: the central building block at the top of an arch or vault

: a lever (as in a keyboard) that actuates a mechanism when depressed

: identify as in botany or biology, for example

: provide with a key

: vandalize a car by scratching the sides with a key

: regulate the musical pitch of

: harmonize with or adjust to