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bona fide [bona fide 词源字典]: 1540s, Latin, literally "in good faith," ablative of bona fides "good faith" (see faith). Originally used as an adverb, later (18c.) also as an adjective. The opposite is mala fide.[bona fide etymology, bona fide origin, 英语词源]
bona fides (n.): by 1838, English pluralization of bona fide, as though it were a noun meaning "guarantee of good faith."
putative (adj.): early 15c., from Middle French putatif, from Late Latin putativus "supposed," from Latin putat-, past participle stem of putare "to judge, suppose, believe, suspect," originally "to clean, trim, prune" (see pave). At first especially in putative marriage, one which, though legally invalid, was contracted in good faith by at least one party. Related: Putatively.
true (adj.): Old English triewe (West Saxon), treowe (Mercian) "faithful, trustworthy, honest, steady in adhering to promises, friends, etc.," from Proto-Germanic *treuwaz- "having or characterized by good faith" (cognates: Old Frisian triuwi, Dutch getrouw, Old High German gatriuwu, German treu, Old Norse tryggr, Danish tryg, Gothic triggws "faithful, trusty"), from PIE *drew-o-, a suffixed form of the root *deru-/*dreu- "be firm, solid, steadfast" (cognates: Lithuanian drutas "firm," Welsh drud, Old Irish dron "strong," Welsh derw "true," Old Irish derb "sure"), with specialized sense "wood, tree" and derivatives referring to objects made of wood (see tree (n.)).

Sense of "consistent with fact" first recorded c. 1200; that of "real, genuine, not counterfeit" is from late 14c.; that of "conformable to a certain standard" (as true north) is from c. 1550. Of artifacts, "accurately fitted or shaped" it is recorded from late 15c. True-love (n.) is Old English treowlufu. True-born (adj.) first attested 1590s. True-false (adj.) as a type of test question is recorded from 1923. To come true (of dreams, etc.) is from 1819.