veteran

A veteran is a person who has served in the military or a person who has obtained a lot of experience in a particular field. (noun)

An example of a veteran is someone who served in the army.
A person who has worked for 20 years in the field of social work is an example of someone who would be described as a veteran in the field.

See veteran in Webster's New World College Dictionary

adjective

noun

1. an old, experienced soldier, etc., esp. one who served in time of war
2. any person who has served in the armed forces
a person of long experience in some occupation or position

See veteran in American Heritage Dictionary 4

(vĕtˈər-ən, vĕtˈrən)

noun

A person who is long experienced or practiced in an activity or capacity: a veteran of political campaigns.
A person who has served in the armed forces: “Privilege, a token income . . . were allowed for veterans of both world wars” (Mavis Gallant).
An old soldier who has seen long service.

adjective