WEIGHTY Copy link • WEIGHTYHeavy, Vid: Cogent, forcible, gravis: firmus, or firmus ad probandum. It appears to me that this is a most weighty argument, firmissimum hoc afferri videtur: it does not appear to me that the reason given by you is a very weighty one, rationem eam, quae a te affertur, non satis firmam puto (Cic.): a very weighty argument, argumentum firmissimum, potentissimum (Quint.): not weighty, infirmus (Quint.).