cotton-tail (n.)

late 13c., "white fibrous substance containing the seeds of the cotton plant," from Old French coton (12c.), ultimately (via Provenal, Italian, or Old Spanish) from Arabic qutn, a word perhaps of Egyptian origin. Also ultimately from the Arabic word are Dutch katoen, German Kattun, Provenal coton, Italian cotone, Spanish algodon, Portuguese algodo.

As "cloth made of cotton," from early 15c. Meaning "the cotton plant" is from c. 1400. As an adjective, "made of cotton," from 1550s. Cotton gin is recorded from 1794 (see gin (n.2)). Philip Miller of the Chelsea Physic Garden sent the first cotton seeds to American colony of Georgia in 1732.

"hindmost part of an animal," Old English tægl, tægel "a tail," from Proto-Germanic *tagla- (source also of Old High German zagal, German Zagel "tail," dialectal German Zagel "penis," Old Norse tagl "horse's tail," Gothic tagl "hair"), from PIE *doklos, from suffixed form of root *dek- (2) "something long and thin" (referring to such things as fringe, lock of hair, horsetail; source also of Old Irish dual "lock of hair," Sanskrit dasah "fringe, wick").

According to OED, the primary sense, at least in Germanic, seems to have been "hairy tail," or just "tuft of hair," but already in Old English the word was applied to the hairless "tails" of worms, bees, etc. But Buck writes that the common notion is of "long, slender shape." As an adjective from 1670s.

Meaning "reverse side of a coin" (opposite the side with the head) is from 1680s; that of "backside of a person, buttocks" is recorded from c. 1300; slang sense of "pudenda" is from mid-14c.; that of "woman as sex object" is from 1933, earlier "act of copulation" with a prostitute (1846). Of descending strokes of letters, from 1590s.

Tails "coat with tails" is from 1857. The tail-race (1776) is the part of a mill race below the wheel. To turn tail "take flight" (1580s) originally was a term in falconry. The image of the tail wagging the dog is attested from 1907. Another Old English word for "tail" was steort (see stark).