n. pl. her·e·sies
a. 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.
b. Adherence to such dissenting opinion or doctrine.
a. A controversial or unorthodox opinion or doctrine, as in politics, philosophy, or science.
b. Adherence to such controversial or unorthodox opinion.
[Middle English heresie, from Old French, from Late Latin haeresis, from Late Greek hairesis, from Greek, a choosing, faction, from haireisthai, to choose, middle voice of hairein, to take.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.