A revolutionary was an individual who dedicated themself to attempting to enact a revolution or uprising.
In his teens, Mikhyl Nevenskoi became part of a group of neo-communist revolutionaries attempting to overthrow the corrupt Soviet Mars colony of Nova Leningrad. His occupation continued to be listed as "revolutionary" even after he left his native 22nd century to become a companion to the Time Lady Leora, as borne out when he helped cause the uprising of Spartacus during a trp to 1st century Rome. (GAME: The Legions of Death [+]J. Andrew Keith, The Doctor Who Role Playing Game (FASA, 1986).)