That supports or advocates a sudden change in the structure and nature of society in accordance with the principles of socialism; specifically (with capital initials) of, relating to, or designating any of various political parties or movements that advocate this, especially a Russian political party active in the early 20th century.
With capital initials. A member of the Russian Socialist Revolutionary party, active in the early 20th century.
Late 19th century; earliest use found in The Times. From socialist + revolutionary.