veteran

Etymology

Borrowed from Middle French vétéran, from Latin veterānus.

noun

1. A person with long experience of a particular activity.
   Private-equity nabobs bristle at being dubbed mere financiers.[…]Much of their pleading is public-relations bluster. Clever financial ploys are what have made billionaires of the industry’s veterans. “Operational improvement” in a portfolio company has often meant little more than promising colossal bonuses to sitting chief executives if they meet ambitious growth targets. That model is still prevalent today. 2013-06-22, “Engineers of a different kind”, in The Economist, volume 407, number 8841, page 70
2. (figurative) A group, animal, etc. with long experience of a particular activity.
   The label has often collaborated with other designers, like Australian shoemaker Teva and American woolwear veteran Pendleton. 1 April 2018, Cristian Bonetto, Lonely Planet Pocket Copenhagen, page 81
3. A person who has served in the armed forces, especially an old soldier who has seen long service; also called a war veteran to distinguish from veterans who weren't in armed conflict.

adj

1. Having had long experience, practice, or service.
   Nothing could be more business-like than the construction of the stout dams, and nothing more gently rural than the limpid lakes, with the grand old forest trees marshalled round their margins like a veteran army that had marched down to drink, only to be stricken motionless at the water’s edge. 1913, Robert Barr, chapter 4, in Lord Stranleigh Abroad
2. Of or relating to former members of the military armed forces, especially those who served during wartime.