heresy
n. C / Un. a belief or opinion that goes against the official rules of a religion or a popular idea. You use this word when someone says something that most people in a group think is wrong or dangerous.
n. a belief or opinion contrary to orthodox religious doctrine, or an opinion profoundly at odds with what is generally accepted. Often carries a historical or theological weight, implying a formal rejection of established authority.
In the past, people were punished for heresy.
The scientist's new theory was considered heresy by his colleagues, who had spent decades defending the old model.
From Middle English heresie, from Old French heresie (modern hérésie), from Latin haeresis, from Ancient Greek αἵρεσις (haíresis, “choice, system of principles”), from αἱρέομαι (hairéomai, “to take for oneself, to choose”), the middle voice of αἱρέω (hairéō, “to take”), possibly from Proto-Indo-European *ser-; see also Welsh herw (“theft, raid”), Ancient Greek στερέω (steréō, “to deprive of”).
Uncountable when referring to the abstract concept of deviance; countable when referring to a specific belief or act.