sect

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A group of people forming a distinct unit within a larger group by virtue of certain refinements or distinctions of belief or practice.
• noun A religious body, especially one that has separated from a larger denomination.
• noun A faction united by common interests or beliefs.

from The Century Dictionary.

• [lowercase or cap.] An abbreviation of section.
• noun A system or body of doctrines or opinions held by a number of persons and constituting the distinctive doctrines of a school, as propounded originally by the founder or founders of the school and (usually) developed or modified by later adherents; also and usually, the body of persons holding such doctrines or opinions; a school of philosophy or of philosophers: as, the sect of Epicurus; the sect of the Epicureans.
• noun A party or body of persons who unite in holding certain special doctrines or opinions concerning religion, which distinguish them from others holding the same general religious belief; a distinct part of the general body of persons claiming the same religious name or origin; especially, such a party of innovators, differing in their beliefs from those who support the older or orthodox views; a party or faction in a religious body; a separate ecclesiastical organization; an ecclesiastical denomination: as, the sects of the Jewish religion (which were not separately organized); the sects of the Christian church (usually separately organized); Mohammedan sects; Buddhist sects.
• noun A religion.
• noun In a general sense, a number of persons holding the same opinions or practising the same customs, or having common associations or interests; a party; following; company; faction.
• noun Kind; sex: originally merely a particular use of sect in sense 4, but now regarded as a form of sex, and as such avoided as incorrect.
• noun Apparel; likeness.
• noun In geometry: A part cut out on a straight line; a limited straight line or rod; the part or piece of a straight line between two definite points (end-points of the sect); a portion of a given straight line, of definite length.
• noun A piece of a range bounded by two points.
• noun Two points, A and B, upon a straight adjective
• In mathematics, of sects; operating with sects.
• noun A part cut off; a cutting; scion.

from the GNU version of the Collaborative International Dictionary of English.

• noun Those following a particular leader or authority, or attached to a certain opinion; a company or set having a common belief or allegiance distinct from others; in religion, the believers in a particular creed, or upholders of a particular practice; especially, in modern times, a party dissenting from an established church; a denomination; in philosophy, the disciples of a particular master; a school; in society and the state, an order, rank, class, or party.
• noun obsolete A cutting; a scion.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun An offshoot of a larger religion; a group sharing particular (often unorthodox) political and/or religious beliefs.
• noun A group following a specific ideal or a leader.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a subdivision of a larger religious group
• noun a dissenting clique