Definitions
1.nounA person with long experience of a particular activity.
2.nounA group, animal, etc. with long experience of a particular activity.
3.nounA 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 that weren't in armed conflict.
4.adjectiveHaving had long experience, practice, or service.
5.adjectiveOf or relating to former members of the military armed forces, especially those who served during wartime.