Lewis & Short

cognōmĭno, āvi, ātum, 1, v. a. [cognomen].

  1. I. To furnish with a surname, to surname, denominate (mostly post-Aug.; only once in Cic.): amaracum Phrygium, Plin. 21, 11, 39, § 67; 21, 3, 7, § 10; * Quint. 4, 1, 2; Suet. Tib. 17.
    In part. pass.: quo ex facto ipse posterique ejus Torquati sunt cognominati, Quadr. ap. Gell. 9, 13, 19; Suet. Aug. 7; Plin. 35, 10, 37, § 112; 33, 10, 17, § 133; Flor. 3, 5, 1: verba cognominata, i. e. synonyms, * Cic. Part. Or. 15, 53.
  2. II. Rarely in gen., to name, call: MacedoniaEmathia cognominata est, Just. 7, 1, 1; so id. 15, 2, 11; Gell. 2, 22, 8.