c. 1400, "an inspector, one who makes inquiries," from Anglo-French inquisitour, Old French inquisiteur, or directly from Latin inquisitor "searcher, examiner; a legal investigator, collector of evidence," agent noun from Latin inquirere (see inquire). As the title of an officer of the Inquisition, from 1540s. Related: Inquisitorial. Of the fem. forms, inquisitress (1727) is senior to inquisitrix (1825).