The Collaborative International Dictionary of English v.0.48:

Sect \Sect\ (s[e^]kt), n. [L. secare, sectum, to cut.]
   A cutting; a scion. [Obs.] --Shak.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Sect \Sect\ (s[e^]kt), n. [F. secte, L. secta, fr. sequi to
   follow; often confused with L. secare, sectum, to cut. See
   Sue to follow, and cf. Sept, Suit, n.]
   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.
   [1913 Webster]

         He beareth the sign of poverty,
         And in that sect our Savior saved all mankind. --Piers
                                                  Plowman.
   [1913 Webster]

         As of the sect of which that he was born,
         He kept his lay, to which that he was sworn. --Chaucer.
   [1913 Webster]

         The cursed sect of that detestable and false prophet
         Mohammed.                                --Fabyan.
   [1913 Webster]

         As concerning this sect [Christians], we know that
         everywhere it is spoken against.         --Acts xxviii.
                                                  22.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sect
    n 1: a subdivision of a larger religious group [syn: sect,
         religious sect, religious order]
    2: a dissenting clique [syn: faction, sect]

Moby Thesaurus II by Grady Ward, 1.0:

62 Moby Thesaurus words for "sect":
   Babi, Babism, Bahaism, Brahmanism, Brahmoism, Buddhism,
   Chen Yen Buddhism, Christianity, adherents, affiliation,
   anthroposophy, body, branch, breakaway group, cabal, camp, caucus,
   church, class, clique, communion, community, confession,
   connection, creed, cult, denomination, disciples, division,
   ethnic group, faction, faith, fellowship, followers, group,
   interest, interest group, ism, minority group, offshoot, order,
   organization, party, persuasion, political party, pressure group,
   religious order, schism, school, school of thought, sectarism,
   segment, set, side, silent majority, society, splinter,
   splinter group, variety, version, vocal minority, wing



Easton's 1897 Bible Dictionary:

Sect
   (Gr. hairesis, usually rendered "heresy", Acts 24:14; 1 Chr.
   11:19; Gal. 5:20, etc.), meaning properly "a choice," then "a
   chosen manner of life," and then "a religious party," as the
   "sect" of the Sadducees (Acts 5:17), of the Pharisees (15:5),
   the Nazarenes, i.e., Christians (24:5). It afterwards came to be
   used in a bad sense, of those holding pernicious error,
   divergent forms of belief (2 Pet. 2:1; Gal. 5:20).