c. 1300, "mantle fastener," from Old French tassel "tassel, fringe, hem; a fastening, clasp" (12c., Modern French tasseau), from Vulgar Latin *tassellus, said to be from Latin taxillus "small die or cube," a diminutive of talus "knucklebone (used as a die in gaming), ankle" (see talus (n.1)). But OED finds this doubtful and calls attention to the variant form tossel and suggests association with toss (v.). Meaning "hanging bunch of small cords" is first recorded late 14c.

term of contempt in British slang, by 1977, probably from slang toss off "act of masturbation" (1735). Agent noun from toss (v.). Compare jerk (n.).

"heavy drinker," 1560s, from toss (v.) + pot (n.1).

"even matter," 1809, from earlier sense of "a flipping of a coin to arrive at a decision" (c. 1700), from verbal phrase, from toss (v.) + up (adv.).