swanky adj.

"stylish, classy, posh," 1913, from earlier noun or verb; "A midland and s.w. dial. word taken into general slang use at the beginning of the 20th cent." [OED]; compare swank (n.) "ostentatious behavior," noted in 1854 as a Northampton word; swank (v.), from 1809 as "to strut, behave ostentatiously." Perhaps ultimately from Proto-Germanic *swank-, from PIE *sweng(w)-, 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.)). Perhaps the notion is of "swinging" the body ostentatiously (compare swagger).

A separate word-thread derives from Old English swancor "pliant, bending," and from this comes swanky (n.) "active or clever young fellow" (c. 1500).

adjective suffix, "full of or characterized by," from Old English -ig, from Proto-Germanic *-iga- (source also of Dutch, Danish, German -ig, Gothic -egs), from PIE -(i)ko-, adjectival suffix, cognate with elements in Greek -ikos, Latin -icus (see -ic). Originally added to nouns in Old English; used from 13c. with verbs, and by 15c. even with other adjectives (for example crispy). Adjectives such as hugy, vasty are artificial words that exist for the sake of poetical metrics.