false note

Noun

1. An incorrect note which is sung or played in a musical performance.
   • Sometimes he even thrums a little on the piano, and takes a part in a trio, in which his voice can generally be distinguished by a certain quavering tone, and an occasional false note. - 1819, Washington Irving, “The...
   • Her fingers wavered on the piano—she struck a false note, confused herself in trying to set it right, and dropped her hands angrily on her lap. - 1860, Wilkie Collins, chapter 15, in The Woman in White:
2. Of a remark or narrative, an indication (as discerned by the listener or reader) of untruth, insincerity, or inconsistency.
   • [H]is words were grave, his manner was earnest, and his speech came from the fulness of his heart. If there had been a false note, a false look, Harry would have detected both, […] - 1900, Fergus Hume, “Mr Baltic,...
   • The screenplay . . . even suggests that this contributed to the false note on which The African Queen actually ends. - 1990 September 14, Janet Maslin, “Movie Review: White Hunter Black Heart (1990)”, in New York Times,...
   • Shreve creates a little world, peoples it with believable characters, and puts them through agonizing and joyful moments without a false note or a dissonant figure of speech. - 2010 December 10, Brigitte Weeks, “Book...
3. Of a non-verbal display or presentation, an indication of incongruity or inappropriateness.
   • The only false note in an otherwise classic and elegant collection was the gratuitous flash of black fishnet stockings and suspenders under otherwise unremarkable paisley and floral shirts. - 2009 February 20, Hilary...