(transitive) To cause (something) to be out of tune; to make incapable of harmony, or of harmonious action.
1800, Thomas Jefferson, letter dated 4 July, 1800, in Henry S. Randall, The Life of Thomas Jefferson, New York: Derby & Jackson, 1858, Volume 2, Chapter 11, p. 565,
Our forte-piano arrived a day or two after you left us. It has been exposed to a great deal of rain, but being well covered was only much untuned.
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