The Collaborative International Dictionary of English v.0.48:

Heterodox \Het"er*o*dox\, a. [Gr. ?; ? other + ? opinion; cf. F.
   h['e]t['e]rodoxe.]
   1. Contrary to, or differing from, some acknowledged
      standard, as the Bible, the creed of a church, the decree
      of a council, and the like; not orthodox; heretical; --
      said of opinions, doctrines, books, etc., esp. upon
      theological subjects.
      [1913 Webster]

            Raw and indigested, heterodox, preaching. --Strype.
      [1913 Webster]

   2. Holding heterodox opinions, or doctrines not orthodox;
      heretical; -- said of persons. --Macaulay. --
      Het"er*o*dox`ly, adv. -- Het"er*o*dox`ness, n.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Heterodox \Het"er*o*dox\, n.
   An opinion opposed to some accepted standard. [Obs.] --Sir T.
   Browne.
   [1913 Webster]

WordNet (r) 3.0 (2006):

heterodox
    adj 1: characterized by departure from accepted beliefs or
           standards [syn: dissident, heretical, heterodox]

Moby Thesaurus II by Grady Ward, 1.0:

107 Moby Thesaurus words for "heterodox":
   Albigensian, Arian, Bohemian, Catharist, Donatist, Ebionitist,
   Erastian, Gnostic, Jansenist, Jansenistic, Jovinianist,
   Jovinianistic, Lollard, Manichaean, Monophysite, Monophysitic,
   Montanist, Montanistic, Pelagian, Sabellian, Waldensian, Wyclifite,
   aberrant, abroad, adrift, all abroad, all off, all wrong, amiss,
   antinomian, apocryphal, askew, astray, at fault, awry, beat,
   beside the mark, breakaway, corrupt, deceptive, defective,
   delusive, deviant, deviational, deviative, dissident, distorted,
   emanationist, errant, erring, erroneous, fallacious, false,
   far out, faultful, faulty, flawed, free and easy, fringy,
   heretical, hippie, hylotheist, hylotheistic, illogical, illusory,
   individualistic, informal, inner-directed, kinky, maverick,
   nonconformist, nonorthodox, not cricket, not done, not kosher,
   not right, not true, off, off the track, offbeat, original, out,
   pantheist, pantheistic, peccant, perverse, perverted, schismatic,
   sectarian, self-contradictory, straying, unaccepted, unapproved,
   unauthentic, unauthoritative, uncanonical, unconventional,
   unfactual, unfashionable, unorthodox, unproved, unscriptural,
   unsound, untrue, way out, wide, wrong