THESAURUS
off key
abnormal, absonant, anomalous, atonal, cacophonous, cracked, deviant, diaphonic, disconsonant, discordant, disharmonic, disharmonious, dissonant, divergent, flat, grating, harsh, immelodious, inharmonic, inharmonious, musicless, nonmelodious, off, off-tone, out of pitch, out of tone, out of tune, raucous, sharp, shrill, sour, strident, tuneless, unharmonious, unmelodious, unmusical, unnatural, unregular, untunable, untuned, untuneful