dis·so·nant 
(dĭsə-nənt)
(dĭsə-nənt)adj.
1. Harsh and inharmonious in sound; discordant.
2. Being at variance; disagreeing.
3. Music Constituting or producing a dissonance.
[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 the Appendix of Indo-European roots.]
disso·nant·ly adv.