Lewis Short
(adjective) : dĕcennālis, e, decem-annus
* Of ten years, decennial (late Lat.; cf. decennis): bellum, i. e. Caesar's in Gaul,Amm. 15, 12, 6; of the Trojan war,Hier. adv. Jovin. 1, 48.
* Subst.: DECENNALIA (ium, n.), a festival celebrated every ten years after the time of Augustus, Trebell. Gallien. 21, 5; Inscr. Grut. 116, 4; v. decennis fin.
Charlton T. Lewis, Charles Short, A Latin Dictionary