noun
moralist
Refers to a person who advocates or practices moral principles, often with a connotation of being judgmental or preachy.
彼は厳格なモラリストで、他人の行動によく口を出す。
He is a strict moralist who often criticizes others' behavior.
道徳家 is a native Japanese term for a moralist, often with a more neutral or positive connotation, while モラリスト can carry a slightly more critical or Western philosophical nuance.
Borrowed from English 'moralist', ultimately from Latin 'moralis'.