(1):

(n.) Pertaining to a sect, or to sects; peculiar to a sect; bigotedly attached to the tenets and interests of a denomination; as, sectarian principles or prejudices.

(2):

(n.) One of a sect; a member or adherent of a special school, denomination, or religious or philosophical party; one of a party in religion which has separated itself from established church, or which holds tenets different from those of the prevailing denomination in a state.