Describes ideas, policies, people, or movements that favor reform, innovation, or forward-looking change. Often used in political, social, or cultural contexts.
He has progressive ideas.
That political party advocates progressive policies.
進歩的 stresses forward-looking, reform-minded attitudes, whereas リベラル more broadly means open-minded or tolerant, especially in political contexts.
保守的 favors keeping things as they are, whereas 進歩的 favors progress and forward-looking change.
Compound of 進歩 (progress) + 的 (-like, -ish). The suffix 的 turns the noun into an adjectival noun meaning 'having the nature of progress'.