Familiar
Middle English (in the sense ‘intimate’, ‘on a family footing’): from Old French familier, from Latin familiaris, from familia ‘household servants, family’, from famulus ‘servant’.
wiktionary
From Latin familiāris(“pertaining to servants; pertaining to the household”). Doublet of familial. Displaced native Old English hīwcūþ.
etymonline
familiar (adj.)
mid-14c., "intimate, very friendly, on a family footing," from Old French famelier "related; friendly," from Latin familiaris "domestic, private, belonging to a family, of a household;" also "familiar, intimate, friendly," a dissimilation of *familialis, from familia (see family).
From late 14c. as "of or pertaining to one's family." Of things, "known from long association," from late 15c. Meaning "ordinary, usual" is from 1590s.
The noun meaning "demon, evil spirit that answers one's call" is from 1580s (familiar spirit is attested from 1560s); earlier as a noun it meant "a familiar friend" (late 14c.). The Latin plural, used as a noun, meant "the slaves," also "a friend, intimate acquaintance, companion."
