Gallant
Middle English (in the sense ‘finely dressed’): from Old French galant, from galer ‘have fun, make a show’, from gale ‘pleasure, rejoicing’.
wiktionary
From Middle English galant, galaunt, from Old French galant(“courteous; dashing; brave”), present participle of galer(“to rejoice; make merry”), from gale(“pomp; show; festivity; mirth”); either from Frankish *wala-(“good, well”), from Proto-Germanic *wal-, from Proto-Indo-European *welh₁-(“to choose, wish”); or alternatively from Frankish *gail(“merry; mirthful; proud; luxuriant”), from Proto-Germanic *gailaz(“merry; excited; luxurious”), related to Dutch geil(“horny; lascivious; salacious; lecherous”), German geil(“randy; horny; lecherous; wicked”), Old English gāl(“wanton; wicked; bad”).
From French
etymonline
gallant (adj.)
mid-15c., "showy, finely dressed; gay, merry," from Old French galant "courteous," earlier "amusing, entertaining; lively, bold" (14c.), present participle of galer "rejoice, make merry," which is of uncertain origin. Perhaps from a Latinized verb formed from Frankish *wala- "good, well," from Proto-Germanic *wal- (source also of Old High German wallon "to wander, go on a pilgrimage"), from PIE root *wel- (2) "to wish, will" (see will (v.)), "but the transition of sense offers difficulties that are not fully cleared up" [OED]. Sense of "politely attentive to women" was adopted early 17c. from French. Attempts to distinguish this sense by accent are an 18c. artifice.
gallant (n.)
mid-15c., "man of fashion and pleasure," earlier "dissolute man, rake" (early 15c.); from gallant (adj.). As "one who is particularly attentive to women" probably by late 15c.
