A person who actively promotes or participates in a revolution, whether political, social, or intellectual.
彼は若い頃、革命家として活動していた。
In his youth, he was active as a revolutionary.
その革命家の思想は多くの人に影響を与えた。
The revolutionary's ideas influenced many people.
Compound of 革命 (revolution) and 家 (suffix for a person engaged in a profession or activity).