decennalia
DECENNA´LIAor DECE´NNIA, a festival celebrated with games every ten years by the Roman emperors. This festival owed its origin to the fact that Augustus refused the supreme power when offered to him for his life, and would only consent to accept it for ten years; and when these expired, for another period of ten years, and so on to the end of his life. The memory of this comedy, as Gibbon has happily called it, was preserved to the last ages of the empire by the festival of the Decennalia, which was solemnised by subsequent emperors every tenth year of their reign, although they had received the imperium for life, and not for the limited period of ten years. (Dio Cass., 54.12, 58.24, 76.1; Trebell. Poll. Salonin. 3, Gallien. 7. Cf. Eichstaedt, Opusc. Acad. 208 ff.)
[W.S] [A.S.W]or Decennia. A festival celebrated with games every ten years by the Roman emperors. This festival owed its origin to the fact that Augustus refused the supreme power when it was offered to him for life, and would only consent to accept it for ten years; and when these expired, for another period of ten years; and so on to the end of his life. The memory of this comedy, as Gibbon has called it, was preserved to the last ages of the Empire by the festival of the Decennalia, which was solemnized by subsequent emperors every tenth year of their reign, although they had received the imperium for life, and not for the limited period of ten years (Dio Cass. liii. 16; liv. 12; lviii. 24; lxxvi. 1).