英语词源字典 - 在线词源网站

bathing (n.)[bathing 词源字典]: 1540s, verbal noun from bathe (v.). Bathing suit is recorded from 1852 (bathing costume from 1830); bathing beauty is 1920, from vaudeville.[bathing etymology, bathing origin, 英语词源]
bikini (n.): "low-waisted two-piece women's bathing suit," 1948, from French coinage, 1947, named for U.S. A-bomb test of June 1946 on Bikini, Marshall Islands atoll, locally Pikinni and said to derive from pik "surface" and ni "coconut," but this is uncertain. Various explanations for the swimsuit name have been suggested, none convincingly, the best being an analogy of the explosive force of the bomb and the impact of the bathing suit style on men's libidos (compare c. 1900 British slang assassin "an ornamental bow worn on the female breast," so called because it was very "killing").
Bikini, ce mot cinglant comme l'explosion même ... correspondant au niveau du vêtement de plage à on anéantissement de la surface vêtue; à une minimisation extrême de la pudeur. [Le Monde, 1947]
As a style of scanty briefs, from 1960. Variant trikini (1967), with separate bra cups held on by Velcro, falsely presumes a compound in bi-.
suntan (v.): also sun-tan, 1821, from sun (n.) + tan (v.). Related: Suntanned; suntanning. As a noun from 1888. Originally an indication of outdoor laboring; considered as an enhancement to beauty or proof of idleness from 1920s: F.L. Allen, chronicler of the decade ("Only Yesterday"), notes 1929 as the year that "on the sands of a thousand American beaches, girls pulled down the shoulder-straps of their bathing suits to acquire fashionably tanned backs ...."
topless (adj.): of women, "bare-breasted," 1966, from top (n.1) + -less. Earlier it was used of men's bathing suits (1937) and women's (1964). Earliest sense is "without a visible summit; immeasurably high" (1580s).