"You canker blossom!" 3 Shakespearean Insults
1867, in literal sense, from over + tone (n.); a loan-translation of German Oberton, first used by German physicist Hermann Ludwig Ferdinand von Helmholtz (1821-1894) as a contraction of Overpartialton "upper partial tone." Figurative sense of "subtle implication" is from 1890, first attested in writings of William James.
See under harmonic.