mid-14c., "musical pitch, musical sound or note," especially considered with reference to its qualities (pitch, timbre, volume, etc.); from Old French ton , Anglo-French toen "musical sound, speech, words" (13c.) and directly from Latin tonus "a sound, tone, accent," literally "stretching" (in Medieval Latin, a term peculiar to music). This is from Greek tonos "vocal pitch, raising of voice, accent, key in music," originally "a stretching, tightening, taut string," which is related to teinein "to stretch" (from PIE root *ten- "to stretch").

The sense of "manner of speaking, modulation or inflection of the voice to express feeling, etc.," is from c. 1600. Extended by 1765 to "style in speaking or writing which reveals attitude." In physiology, in reference to firmness of body, from 1660s. As "prevailing state of manners" from 1735; also compare ton (n.2).

By early 15c. in reference to any sound (rendering Latin sonus ). Of colors in paintings, by 1816. By 1893 in photography as "color or shade of a finished picture," often due to chemical processes. As an electrically produced sound made by a telephone, by 1878. Tone-deaf is by 1880; tone-poem by 1845.

"impart (musical) tone to," 1811, from tone (n.). In photography, "alter the color of to give greater brilliancy," by 1868. To tone (something) down originally was in painting (1831), "soften the colors of a picture;" the general or transferred sense of "reduce, moderate, give a more subdued character to" is by 1847.

Middle English had tonen (v.) "sing (a note) with proper musical quality, intone" (late 14c.). Related: Toned ; toning .