late 14c. (early 14c. in Anglo-French), from Old French grave, graue, apparently a misspelling of grané "sauce, stew," with -n- misread for -u- -- the character used for -v- in medial positions in words in medieval manuscripts. The French word probably originally meant "properly grained, seasoned," from Latin granum "grain, seed" (see grain (n.)). Meaning "money easily acquired" first attested 1910; gravy train (1909) originally was railroad slang for a short haul that paid well. Gravy-boat "small, deep dish for holding gravy or sauce" is from 1827.
