heresy

noun

her·​e·​sy ˈher-ə-sē 

ˈhe-rə-

plural heresies

1

a

: adherence to a religious opinion contrary to church dogma (see dogma sense 2)

They were accused of heresy.

b

: an opinion or doctrine contrary to church dogma

He was preaching heresies.

c

: denial of a truth made known through divine inspiration by a baptized member of the Roman Catholic Church

2

a

: dissent or deviation from a dominant theory, opinion, or practice

To disagree with the party leadership was heresy.

b

: an opinion, doctrine, or practice contrary to the truth or to generally accepted beliefs or standards

… won his Nobel for saying way back in 1986 that markets really weren't that efficient (heresy at the time) …

—Rana Foroohar

our democratic heresy which holds that … truth is to be found by majority vote

—M. W. Straight

Synonyms of heresy

• dissent
• heterodoxy

Examples of heresy in a Sentence

They were accused of heresy.

He was preaching dangerous heresies.

Recent Examples on the Web

A day that started all warm and quiet and cozy has now spiraled into screams of heresy and hearsay punctuated by occasional wrestling matches on the carpet. —Paul Cappiello, Louisville Courier Journal, 7 Nov. 2025

That large firms armed with experts would fall into the trap of bidding in auctions in which the winner is cursed to lose was major heresy to economists. —Emma Burleigh, Fortune, 21 Oct. 2025

In the value-investing, human discretion driven ethos of PIMCO this was heresy. —Vineer Bhansali, Forbes.com, 9 Sep. 2025

The town’s new math is savage in that outrage decays, audiences pay, so ‘respect for Trump’s chops’ is suddenly a hard-nosed business note, not heresy. —Brie Stimson , Larry Fink, FOXNews.com, 3 Sep. 2025

Word History

Etymology

Middle English heresie, borrowed from Anglo-French, borrowed (with assimilation to the suffix -ie -y entry 2) from Late Latin haeresis, heresis "school (of philosophy or theology), sect, belief contrary to church dogma," borrowed from Greek haíresis "act of taking, choice, course of action or thought, system of principles, sect, faction," from haireîn "to take, grasp, (middle voice) obtain, choose, prefer" (of obscure origin) + -sis -sis

First Known Use

13th century, in the meaning defined at sense 1a

Kids Definition

heresy

noun

her·​e·​sy ˈher-ə-sē 

plural heresies

1

: religious opinion that is opposed to the doctrines of a church

2

: opinion that is opposed to a generally accepted belief