parsnip n.

biennial plant of Eurasia; its pale yellow root has been used as a food from ancient times; c. 1500, parsnepe, a corruption (by influence of Middle English nepe "turnip;" see neep) of Middle English passenep (late 14c.), from Old French pasnaise "parsnip," also "male member" (Modern French panais) and directly from Latin pastinaca "parsnip, carrot," from pastinum "two-pronged fork" (related to pastinare "to dig up the ground"). The plant was so called from the shape of the root. The parsnip was considered a kind of turnip. The unetymological -r- in the English word is unexplained; cognate Old High German, German, and Dutch pastinak are closer to the Latin original.