Origin and history of tan

c. 1400, tannen, in part from late Old English tannian "convert hides into leather" (by steeping them in liquid containing tannin), from Medieval Latin tannare "tan, dye a tawny color" (c. 900), from tannum "crushed oak bark," used in tanning leather. This is believed to be from a Celtic source, such as Breton tann "oak tree."*

By extension, "convert to leather" by other means. The sense of "make (the skin, face, etc.) brown by exposure to the sun" (as tanning does to hides) is recorded by 1520s; the intransitive sense "become tanned by the rays of the sun" also is from 1520s; compare sun-tan.

To tan (someone's) hide in the figurative sense of "beat, flog, thrash" is from 1660s. Related: Tanned; tanning.

* German Tanne "fir tree" (as in Tannenbaum) might be a transferred meaning from the same Celtic source.

c. 1600, "crushed bark of the sort used in tanning," from tan (v.) and perhaps also from Middle English tannedust, powder of tanne "oak bark powdered and used medicinally or in tanning" (late 14c.), from Old French tan, ten and directly from Medieval Latin tannum.

The meaning "a browning of the skin by exposure to the sun, bronze color imparted to skin by exposure to sun" is by 1749 (compare sun-tan). Tan-line is attested by 1979.

As a name for a brownish color, in any context (originally fashion), it is recorded by 1888. As an adjective from 1620s; the meaning "of the yellowish-gray color of tanned leather" is by 1660s. Spent tan-bark was used in gardening and spread on enclosures for riding horses, hence tan had for a time 19c. a figurative association with the circus ring.