A specialist in a given field whose opinion is highly valued, especially in one of the fine arts or in matters of taste.
A person with long experience of a particular activity.
A group, animal, etc. with long experience of a particular activity.
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.
Having had long experience, practice, or service.
Of or relating to former members of the military armed forces, especially those who served during wartime.