Sĕcundus Copy link Outline I. C. Plinius Secundus, the writer on natural history. ...II. C. Plinius Caecilius Secundus, his nephew ... • Sĕcundus, i, m.; Sĕcunda, ae, f. [1. secundus], a Roman proper name. I. C. Plinius Secundus, the writer on natural history.— II. C. Plinius Caecilius Secundus, his nephew: OCTAVIA Q. F. SECVNDA, Inscr. Grut. 445, 2; cf. Varr. L. L. 9, § 60 Müll.