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."
adjectival word-forming element meaning "making, creating," from French -fique and directly from Latin -ficus "making, doing," combining form of facere "to make" (from PIE root *dhe- "to set, put").
multiplicative word-forming element attached to numerals, from Old English -feald, Northumbrian -fald, from Proto-Germanic *-falda- (cognates: Old Saxon -fald, Old Frisian -fald, Old Norse -faldr, Dutch -voud, German -falt, Gothic falþs), combining form of *falthan, from PIE *polt-, extended form of root *pel- (2) "to fold."
The same root yielded fold (v.) and perhaps also Greek -ploid, -plos and Latin -plus (see -plus). Native words with it have been crowded out by Latinate double, triple, etc., but it persists in manifold, hundredfold, etc.