rāpum, i, n. akin to Gr. ῥάφη, ῥαφάνη (collat. form rāpa, ae, f., Col. 11, 3, 16; Scrib. Comp. 176; 177), a turnip, rape: Brassica rapa, Linn.; Varr. R. R. 1, 59, 4; Col. 2, 10, 22 sq.; Plin. 18, 13, 33, § 125; flung at one as an insult, Suet. Vesp. 4.

— A knob or lump formed by the roots of a tree: magnarum arborum truncos cum rapo suo transtulit, Sen. Ep. 86, 17; cf. id. ib. 86, 18.