A person who campaigns for a person running for political office or works, or supports, in an organised and active way towards a goal; an activist.
Someone with experience in a certain field.
A person who has served in a military campaign.
A military veteran.
A young person who agitates for political or other reform; a young person with a rebellious disposition.
From the late-19th to the early-20th century, a member of a movement that campaigned for reform of the Ottoman Empire.