noun
liberalist
Refers to a person who advocates liberal principles, often in politics or social thought. The term is a direct loan from English and is used similarly to its English counterpart.
彼は熱心なリベラリストで、個人の自由を何よりも大切にしている。
He is a passionate liberalist who values individual freedom above all else.
リベラル is an adjective or noun meaning 'liberal', while リベラリスト specifically refers to a person who is a liberalist.
Borrowed from English 'liberalist'.