progressionist; progressivist
A person who advocates for progress or progressive ideas, often in political, social, or educational contexts. The term is relatively formal and may be used in historical or ideological discussions.
He is known as a progressionist in the field of education.
The progressionists strongly advocated for social reform.
進歩主義 is the abstract concept of progressivism, while 進歩主義者 refers to a person who adheres to that ideology.
保守主義者 is a conservative, the ideological opposite of a progressionist.
Compound of 進歩 (progress) + 主義 (principle, -ism) + 者 (person). The term is a straightforward Sino-Japanese construction.