key n
2 (figurative) answer, clue, cue, explanation, guide, indicator, interpretation, lead, means, pointer, sign, solution, translation adj
3 basic, chief, crucial, decisive, essential, fundamental, important, leading, main, major, pivotal, principal
3 minor, secondary, subsidiary, superficial
key in
enter, input, keyboard, type
low-key
keeping a low profile, low-pitched, muffled, muted, played down, quiet, restrained, subdued, toned down, understated
off key
discordant, dissonant, inharmonious, jarring, out of keeping, out of tune