Lewis & Short

† dĭădūmĕnus, a, um, adj., = διαδούμενος,

  1. I. wearing a diadem: juvenis, Plin. 34, 8, 19, § 55: statua, Sen. Ep. 65, 5.
  2. II. Antoninus Diadumenus, a Roman emperor, son and successor of Macrinus; cf. Lampr. Anton. Diadum. 4.