1Designating a person who considers himself or herself to be justified or righteous before God by virtue of his or her own efforts, especially by good works and adherence to religious law as contained in the Scriptures.
2Of a person: that has justified or excused his or her own actions; (of conduct, behaviour, etc.) that justifies itself, intrinsically justified; (also occasionally) justified or excused by the person responsible.
Mid 17th century. From self- + justified.