colloquial shortening of gentleman, by 17c. (in early uses it is difficult to distinguish the shortening from the common abbreviation gent.), which is perhaps the origin of this use. "Early in the nineteenth century the word was colloquial and slightly jocular; about 1840 its use came to be regarded as a mark of low breeding" [OED].
*genə-, also *gen-, Proto-Indo-European root meaning "give birth, beget," with derivatives referring to procreation and familial and tribal groups.
It forms all or part of: Antigone; autogenous; benign; cognate; congener; congenial; congenital; connate; cosmogony; cryogenic; degenerate; engender; engine; epigone; eugenics; -gen; gendarme; gender; gene; genealogy; general; generate; generation; generic; generous; genesis; -genesis; genial; -genic; genital; genitive; genius; genocide; genotype; genre; gens; gent; genteel; gentile; gentle; gentry; genuine; genus; -geny; germ; german (adj.) "of the same parents or grandparents;" germane; germinal; germinate; germination; gingerly; gonad; gono-; gonorrhea; heterogeneous; homogeneous; homogenize; homogenous; impregnate; indigenous; ingenious; ingenuous; innate; jaunty; kermes; kin; kindergarten; kindred; king; kind (n.) "class, sort, variety;" kind (adj.) "friendly, deliberately doing good to others;" Kriss Kringle; malign; miscegenation; nada; naive; nascent; natal; Natalie; nation; native; nature; nee; neonate; Noel; oncogene; ontogeny; photogenic; phylogeny; pregnant (adj.1) "with child;" primogenitor; primogeniture; progenitor; progeny; puisne; puny; renaissance; theogony; wunderkind.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit janati "begets, bears," janah "offspring, child, person," janman- "birth, origin," jatah "born;" Avestan zizanenti "they bear;" Greek gignesthai "to become, happen," genos "race, kind," gonos "birth, offspring, stock;" Latin gignere "to beget," gnasci "to be born," genus (genitive generis) "race, stock, kind; family, birth, descent, origin," genius "procreative divinity, inborn tutelary spirit, innate quality," ingenium "inborn character," possibly germen "shoot, bud, embryo, germ;" Lithuanian gentis "kinsmen;" Gothic kuni "race;" Old English cennan "beget, create," gecynd "kind, nature, race;" Old High German kind "child;" Old Irish ro-genar "I was born;" Welsh geni "to be born;" Armenian cnanim "I bear, I am born."
"extremely cautiously" (of movements, etc.), c. 1600; earlier "elegantly, daintily" (1510s), of unknown origin. Perhaps [OED] from Old French gensor, comparative of gent "dainty, delicate," from Latin gentius "(well)-born" (see gentle).
Old English ganot, name of a kind of sea-bird, from Proto-Germanic *ganton- (source also of Dutch gent, Middle High German ganiz, Old High German ganazzo "a gander"), from PIE *ghans- "a goose" (see goose (n.)). Old French gante is from Germanic.
late 14c., "contrary, opposing," from Old French advers, earlier avers (13c., Modern French adverse) "antagonistic, unfriendly, contrary, foreign" (as in gent avers "infidel race"), from Latin adversus "turned against, turned toward, fronting, facing," figuratively "hostile, adverse, unfavorable," past participle of advertere "to turn toward," from ad "to" (see ad-) + vertere "to turn, turn back; be turned; convert, transform, translate; be changed" (from PIE root *wer- (2) "to turn, bend"). For distinction of use, see averse. Related: Adversely.
"French military police," 1796, from French (they were first organized in France 1790); earlier "mounted trooper" (1540s), from French contraction (14c.) of gens d'armes "men at arms." Gens is plural of gent "nation, people," from Latin gentem (nominative gens) "race, nation, people" (from PIE root *gene- "give birth, beget," with derivatives referring to procreation and familial and tribal groups). For armes see arm (n.2). Related: Gendarmerie, gendarmery. French also had gens de (la) robe "lawyers," which was sometimes borrowed in English.