oldtimer vs veteran

oldtimer and veteran both are nouns.

Word	Noun	Adjective	Verb	Adverb
oldtimer	Yes	No	No	No
veteran	Yes	Yes	No	No

As nouns, oldtimer and veteran are synonyms defined as:

oldtimer and veteran: an experienced person who has been through many battles; someone who has given long service

Other synonyms of oldtimer include old-timer, old hand, old stager, stager, warhorse.

oldtimer (noun)	veteran (noun)
an elderly man	an experienced person who has been through many battles; someone who has given long service
an experienced person who has been through many battles; someone who has given long service	a person who has served in the armed forces
	a serviceman who has seen considerable active service

oldtimer (adjective)	veteran (adjective)
	rendered competent through trial and experience