Origin and history of sway

"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.).

Middle English swingen "cause to move, throw, cast, fling; move, dash, rush;" also "deliver a blow, smite with a weapon," from Old English swingan "to beat, strike; scourge, flog; to rush, fling oneself" (strong verb, past tense swang, past participle swungen). This is from Proto-Germanic *swangwi- (source also of Middle Dutch swingen, Old Saxon, Old High German swingan "to swing," Old Frisian swinga "pour," German schwingen "to swing, swingle, oscillate"), which is of uncertain origin and might be in Germanic only. Swirl, switch, swivel, swoop are sometimes considered to be from the same source. Boutkan finds Pokorny's IE reconstruction implausible for formal and semantic reasons.

The meaning "move freely back and forth," as a body suspended from a fixed point, is recorded by 1540s; that of "move with a swinging step" is by 1854. The transitive sense "cause to sway or oscillate" is from 1550s. From 1660s as "ride on a swing;" colloquially, "be hanged," 1520s.

The sense of "bring about, make happen" is by 1934. Related: Swung; swinging.