ad persuadendum accommodatus: ad persuasionem appositus: firmus ad probandum (cogent; e.g., argumentum): gravis (weighty; e.g., argumentum; comp. Cic., Roscius, Com., 12, 36); a most convincing proof, argumentum gravissimum et firmissimum. [Quint. uses persuasibilis = πιθανός, in three passages.]