1550s, "moving to and fro," present-participle adjective from swing (v.). By 1730 as "made or adapted to turn freely in either direction." The meaning "marked by a free, sweeping movement" is from 1818. The figurative sense of "uninhibited" is from 1958.

"move heavily or unsteadily," 1520s, now provincial or archaic, probably from a Scandinavian source akin to Old Norse sveggja "to swing, sway," from the same source as Old English swingan "to swing" (see swing (v.)). Earlier it meant "swing an object" (c. 1400), "swing or shake freely" (late 15c.). Related: Swagged; swagging (mid-15c.).

obsolete past tense of swing (v.).

"stylish, classy, posh," 1913, from earlier noun or verb (see below); "A midland and s.w. dial. word taken into general slang use at the beginning of the 20th cent." [OED].

Swank (n.) "ostentatious behavior" is noted in 1854 as a Northampton word ("what a swank he cuts!"); swank (v.) is attested from 1809 as "to strut, behave ostentatiously."

Perhaps the group is ultimately from a Germanic root meaning "to swing, turn, toss" (source also of Middle High German swanken "to sway, totter, turn, swing," Old High German swingan "to swing;" see swing (v.)). If so, OED suggests (2nd ed. print, 1989), it is perhaps from the notion of "swinging" the body ostentatiously (compare swagger). Related: Swankpot "ostentatious or boastful person" (1914).

A separate swank word-thread in English is from Old English swancor "pliant, bending," also held to be from the swing root (compare German schwank "pliant," Old Norse svangr "thin, slender, slim"). From this comes a number of words now dialectal or obscure, such as swanky (n.) "active or clever young fellow" (c. 1500), also "small beer, weak fermented drink" (1841); swanking "supple, active."

early 14c., sweien, "move, go, go quickly;" also transitive, "move (something) along, carry," probably from a Scandinavian source (compare Old Norse sveigja "to bend, swing, give way," Old Danish svegja) and perhaps merged with an unrecorded Old English cognate. The whole group might be related to swag (v.) and swing (v.).

The sense of "swing, waver, move in a swaying or sweeping motion" is from late 14c. The meaning "move or bend from side to side," as by excess of weight, is from c. 1500. The transitive sense "cause to move from side to side" is from 1550s (according to OED, it was not common before 19c.) and is perhaps from Low German. The meaning "lean away from the perpendicular" is by 1570s. The figurative sense "cause to be directed toward one side, prejudice" is from 1590s. Related: Swayed; swaying.

"independent or independent-minded voter," by 1946 in Australian English ("This swing voter says he won't swing," letter-to-the-editor headline, Daily Telegraph, Sydney, Sept. 9, 1946); from swing (v.).

So called perhaps because they often "swing" an election to one or the other party, but the image of voter or party support swinging to one candidate or another is older in American politics: "Townsend Sets Out To Swing Voters in 9 States to Landon" (1936 headline); "Politics Swings to Swing to Swing Voters" (1939 headline on candidates incorporating newly popular swing music in their pitches).

1540s, "one who or that which swings," agent noun from swing (v.). Old English swingere (n.) meant "one who strikes, a scourger."

Also "anything big or great; a bold lie" (1580s, a sense now obsolete). The meaning "person who is sexually promiscuous" is from 1964, from the verb in the sense of "engage in promiscuous sex" (also 1964); earlier, more generally, "enjoy oneself unconventionally" (1957). Cant swinger "rogue, rascal, scoundrel" (c. 1500) is perhaps from Flemish or Low German.

"wooden instrument for beating flax," early 14c., from Middle Dutch swinghel "swingle for flax," and partly, with narrowing of sense, from cognate Old English swingell "beating, scourging, punishment, chastisement;" also "stick to beat, whip, scourge, rod," a formation from swingan "to beat, strike, whip" (see swing (v.)) + instrumental suffix -el (1). It later was extended to similar mechanisms.

"pivoted crossbar to which the traces are fastened in a cart, carriage, or plow," late 15c., swingletre, earlier swing-tree (late 14c.), from swing (v.) + tree (n.) in an obsolete Middle English sense of "pole." The elaboration of swing into swingle is perhaps on the notion of "that which swings."

"work shift between a standard day and night shift," 1941; see swing (v.) + shift (n.). Typically 4 p.m. to midnight; said to be so called from the notion of "facing both ways."