An Etymological Dictionary of Astronomy and Astrophysics

A musical sound of definite pitch, consisting of several relatively simple constituents called partial tones, the lowest of which is called the fundamental tone and the others harmonics or overtones.

Etymology (EN): M.E., from O.Fr. ton, from L. tonus “a sound, tone, accent,” literally “stretching,” from Gk. tonos “vocal pitch, raising of voice,” related to teinein “to stretch,” cognate with Pers. tanidan “to spin, weave,” → tension.

Etymology (PE): Ton, loan from Fr., as above.