R / rĕcăvus
adjective

rĕcăvus

fem. rĕ-căva · neut. rĕ-căvum
hollow; arched inward; concave
hollow or arched inward, concave (late Lat.): speculum, Prud. στεφ, 11, 186: palatum, id. Psych. 421: laquearia, Paul. Nol. Carm. 28, 408.