word-forming element, from Latin -farius, -fariam "in (so many) parts," as in bifariam "in two parts or places, in two ways;" multifariam "in many places," an element of disputed origin. Watkins suggests it is from PIE *dwi-dhe- "making two," from roots *dwi- "two" + *dhe- "to put, set." It also has been derived from Latin fari "to say" (as in nefarious), but de Vaan writes that "the alleged semantic development to 'in n ways' is obscure," and he points to the suggestion of a PIE *-dho-, with cognates in Sanskrit dvidha (adv.) "twofold;" tridha "threefold."
In paraphernalia, Mammalia, regalia, etc. it represents Latin or Greek -a (see -a (2)), plural suffix of nouns in -ium (Latin) or -ion (Greek), with formative or euphonic -i-.
as in beatnik, etc., suffix used in word formation from c. 1945, from Yiddish -nik (as in nudnik "a bore"), from Russian -nik, common personal suffix meaning "person or thing associated with or involved in" (compare nudnik; kolkhoznik "member of a kolkhoz"). Rocketed to popularity with sputnik (q.v.), hence its brief vogue in English word-formation, as in robotnik "person behaving with mindless obedience" (1960).