British slang word with varied senses, not all of them certainly connected; see Partridge, who lists two noun uses: "female pudenda" (c. 1845), which might be back-slang from fan, shortening of fanny (in the British sense); and "nothing," in prostitutes' slang from c. 1940; a verbal use, a euphemism for fuck (v.) in oaths, imprecations, expletives (as in naff off), 1959, "making it slightly less obvious than eff" [Partridge]; and an adjective naff "vulgar, common, despicable," which is said to have been used in 1960s British gay slang for "unlovely" and thence adopted into the jargons of the theater and the armed forces.
1828, intransitive, "find fault constantly;" by 1840, intransitive, "annoy by continued scolding, pester with petty complaints," originally a dialectal word meaning "to gnaw" (1825, Halliwell), probably ultimately from a Scandinavian source (compare Old Norse gnaga "to complain," literally "to bite, gnaw," dialectal Swedish and Norwegian nagga "to gnaw"), from Proto-Germanic *gnagan, related to Old English gnagan "to gnaw" (see gnaw). As a noun, 1894, "act of nagging;" by 1925, "person who nags." Related: Nagged; nagger; nagging.
"old horse," c. 1400, nagge "small riding horse, pony," a word of unknown origin, perhaps related to Dutch negge, neg (but these are more recent than the English word), perhaps related in either case to imitative neigh. The term of abuse "a worthless person," often of a woman, is a transferred sense, first recorded 1590s. For "one who annoys by scolding" (by 1925) see nag (v.).
in Hindu mythology, a race of serpent demons, offspring of Kaduru, guardians of the under-regions; 1785, from Sanskrit naga "serpent, snake," a word of unknown origin.
native people of southern Mexico and Central America, including the Aztecs; also their language, 1822, from Spanish, from Nahuatl (Aztecan) Nahuatl, the people's name, "something that makes an agreeable sound; someone who speaks well or speaks one's own language." As a language name, it was usually in the compound form nahuatlahotol-li.
in Greek and Roman mythology, "water nymph," one of the female deities presiding over springs and streams, c. 1600, from Latin Nais, Naias (genitive naiadis), from Greek Naias (plural Naiades) "river nymph," from naiein "to flow," from PIE *naw-yo-, suffixed form of *(s)nau- "to swim, flow, let flow" (from PIE root *sna- "to swim"). Dryden used the Latin singular form Nais, and the plural Naiades is attested in English from late 14c.
"ingenuous, artless, natural," 1590s, from French naïf, literally "naive" (see naive). The masculine form of the French word, but used in English without reference to gender. As a noun, "natural, artless, naive person," first attested 1893, from French, where Old French naif also meant "native inhabitant; simpleton, natural fool."