irrational Copy link Outline 1. rationis expers2. irrătiōnālis, e (late and rare)3. brūtus (dull, senseless) • irrational: 1. rationis expers: Cic. Leg. 1, 7, 22. 2. irrătiōnālis, e (late and rare): Quint. 8, 6, 13: Sen. Ep. 92, init.: still later and of less authority is the form irrationabilis, Vulg. 1 Pet. ii. 12: pseudo-Quint. 3. brūtus (dull, senseless): v. stupid. (Alogus, Gr. ἄλογος, Aug.) See also absurd.