veteran

nouns

a serviceman who has seen considerable active service
"the veterans laughed at the new recruits"
veteran, veteran soldier
a person who has served in the armed forces
ex-serviceman, vet, veteran
an experienced person who has been through many battles; someone who has given long service
old hand, old stager, old-timer, oldtimer, stager, veteran, warhorse

adjectives

rendered competent through trial and experience
"a seasoned traveler"; "veteran steadiness"; "a veteran officer"
seasoned, veteran