ratiōnābilis, e, adj. ratio (post-Aug.; = rationalis, which is in better use), reasonable, rational: natura, Sen. Vit. Beat. 14, 1: virtutes quae ad rationabilem animum pertinent, App. Dogm. Plat. 2, p. 17, 18; cf.: virtutes rationabiles, id. ib.: responsio rationabilis, Vulg. Job, 32, 3: rationabile sine dolo lac, the pure milk of reason, id. 1 Pet. 2, 2: sententia vera et rationabilis, Dig. 5, 1, 2, § 3.

—Comp.: rationabilius esse videtur, Dig. 45, 3, 37.

—Adv.: ratiō-nābiliter, rationally, reasonably, App. Dogm. Plat. 1: errare, Hier. Ep. 39, 5; Macr. Somn. Scip. 2, 11, 17; Amm. 20, 4, 8; Lact. Ep. 61, 17.