gymnosophist n.

Old English nacod "nude, unclothed, bare; empty," also "not fully clothed" (a sense still used in 18c.),  from Proto-Germanic *nakwadaz (source also of Old Frisian nakad, Middle Dutch naket, Dutch naakt, Old High German nackot, German nackt, Old Norse nökkviðr, Old Swedish nakuþer, Gothic naqaþs "naked"), from PIE root *nogw- "naked" (source also of Sanskrit nagna, Hittite nekumant-, Old Persian *nagna-, Greek gymnos, Latin nudus, Lithuanian nuogas, Old Church Slavonic nagu-, Russian nagoi, Old Irish nocht, Welsh noeth "bare, naked").

Of things, "without the usual or customary covering" (of a sword, etc.), from Old English. Applied to qualities, actions, etc., "mere, pure, open to view, unconcealed," from c. 1200; phrase the naked truth is from early 15c. Phrase naked as a jaybird (1943) was earlier naked as a robin (1879, in a Shropshire context); Middle English had naked as a worm (mid-14c.), naked as a needle (late 14c.). Naked eye "the eye unassisted by any instrument" is from 1660s, an unnecessary term before telescopes and microscopes.

"one who makes use of fallacious arguments," late 15c., from Late Latin sophista, an alternative form of sophistes; the earlier form in English was sophister, sophistre (late 14c.). Latin sophistes is from Greek sophistēs "a master of one's craft; a wise or prudent man, one clever in matters of daily life," from sophizesthai "to become wise or learned," from sophos "skilled in a handicraft, cunning in one's craft; clever in matters of everyday life, shrewd; skilled in the sciences, learned; clever; too clever," a word of unknown origin.

Greek sophistēs came to mean "one who gives intellectual instruction for pay," and at Athens, contrasted with "philosopher," it was a term of contempt.

Sophists taught before the development of logic and grammar, when skill in reasoning and in disputation could not be accurately distinguished, and thus they came to attach great value to quibbles, which soon brought them into contempt. [Century Dictionary]

The "learned man" sense in English is attested from 1610s but is rare.