tallow n.

hard animal fat, used to make soap, candles, etc., mid-14c., talwgh, from a source (perhaps an unrecorded Old English word) cognate with Middle Low German talg "tallow," Middle Dutch talch, from Proto-Germanic *talga-, meaning perhaps originally "firm, compact material" (compare Gothic tulgus "firm, solid"). OED says related Scandinavian words probably are from continental Germanic.