Origin: 1400–50; late ME dissonaunte (< AF) < L dissonant- (s. of dissonāns, prp. of dissonāre to sound harsh), equiv. to disson- (deriv. of dissonus discordant; see dis-1, sound) + -ant--ant
[Middle English dissonaunt, from Old French dissonant, from Latin dissonāns, dissonant-, present participle of dissonāre, to be dissonant : dis-, apart; see dis- + sonāre, to sound; see swen- in Indo-European roots.] dis'so·nant·ly adv.