Of or pertaining to a sect or sects; peculiar to a sect: as, sectarian interests; sectarian principles.That inculcates the particular tenets of a sect: as, sectarian instruction; a. sectarian book.Of or pertaining to one who is bigotedly attached to a particular sect; characterized by or characteristic of bigoted attachment to a particular sect or its teachings, interests, etc.n. One of a sect; especially, a person who attaches excessive importance or is bigotedly attached to the tenets and interests of a sect.n. Synonyms See heretic.