heresy

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. An opinion or a doctrine at variance with established religious beliefs, especially dissension from or denial of Roman Catholic dogma by a professed believer or baptized church member.
2. n. Adherence to such dissenting opinion or doctrine.
3. n. A controversial or unorthodox opinion or doctrine, as in politics, philosophy, or science.
4. n. Adherence to such controversial or unorthodox opinion.

Century Dictionary and Cyclopedia

1. n. Any doctrine, opinion, or set of opinions at variance with the established standards of any system, school of thought, or party; an opinion or a doctrine tending to create schism or division; an untenable or a disturbing doctrine of any kind, as in philosophy, science, politics, morality, etc.
2. n. Specifically, in theology, an opinion or a doctrine rejected by the authorities of a church as contrary to the established creed of that church; an interpretation or a theological view of a sacred writing or other standard of religion, or of any distinctive part of it, opposed to that authoritatively established or generally accepted: as, the antinomian heresy. To the Roman Catholic any opinion contrary to the teachings of his church, to the Protestant any opinion contrary to the accepted interpretation of the Scripture, is a heresy. The error must be held by a professed believer; pagan and infidel doctrines are not heresies. Roman Catholic divines distinguish between formal heresies, or tenets contrary to the doctrines of the church which are wilfully and pertinaciously held, and material heresies, or tenets that are heretical but are not so pertinaciously held as to involve the guilt of heresy.

Wiktionary

1. n. religion A doctrine held by a member of a religion at variance with established religious beliefs, especially dissension from Roman Catholic dogma.
2. n. A controversial or unorthodox opinion held by a member of a group, as in politics, philosophy or science.

GNU Webster's 1913

1. n. An opinion held in opposition to the established or commonly received doctrine, and tending to promote a division or party, as in politics, literature, philosophy, etc.; -- usually, but not necessarily, said in reproach.
2. n. (Theol.) Religious opinion opposed to the authorized doctrinal standards of any particular church, especially when tending to promote schism or separation; lack of orthodox or sound belief; rejection of, or erroneous belief in regard to, some fundamental religious doctrine or truth; heterodoxy.
3. n. (Law) An offense against Christianity, consisting in a denial of some essential doctrine, which denial is publicly avowed, and obstinately maintained.

WordNet 3.0

1. n. a belief that rejects the orthodox tenets of a religion
2. n. any opinions or doctrines at variance with the official or orthodox position