veteran

[1]	veteran soldier , old hand , past master , old-timer , trouper , (Colloq) warhorse
[2]	vet , ex-serviceman
[3]	old-timer , oldtimer , old hand , warhorse , old stager , stager

adj.

[1]	experienced , practised , seasoned , mature , long-serving , battle-scarred
[2]	seasoned