c. 1200, "a member of the nobility," also a low rank in the peerage, from Old French baron (nominative ber) "baron, nobleman, military leader, warrior, virtuous man, lord, husband," probably from or related to Late Latin baro "man" (source of Spanish varon, Italian barone), which is of uncertain origin. It is perhaps from Celtic or from Frankish *baro "freeman, man" or another Germanic source. In England the word merged with (probably) cognate Old English beorn "nobleman."
word-forming element, originally a diminutive suffix but not now always felt as one, Middle English, from Old French -et (fem. -ete; Modern French -et, -ette), from Vulgar Latin *-ittum/*-itta (source also of Spanish -eto/-eta, Italian -etto/-etta), of unknown origin. The French forms are reduced to -et in English, but later borrowings of French words in -ette tend to keep that ending.