Entry 1 sense Webster, 1913 Catonian · Ca·to·ni·an · IPA /kəˈtoʊ.ni.ən/ 01 a. Of, pertaining to, or resembling, the stern old Roman, Cato the Censor; severe; inflexible. 1. Of, pertaining to, or resembling, the stern old Roman, Cato the Censor; severe; inflexible.