noun
Refers to a person who adheres to utilitarianism, the ethical theory that actions are right if they promote the greatest happiness for the greatest number.
彼は実利主義者として、政策の結果を重視する。
As a utilitarian, he emphasizes the outcomes of policies.
実利主義 is the abstract concept of utilitarianism, while 実利主義者 refers to a person who follows that philosophy.
Compound of 実利 (practical benefit) + 主義 (principle, -ism) + 者 (person). The term is a calque from English 'utilitarian'.