Heresy
Etymology
From Greek "hairesis," "a choice" or "a choosing," from "haireisthai," "to choose." Strikingly, the word originally meant a school of thought one selected, with no stigma attached. Early Christian usage recast that act of choosing your own view as an offense against received truth, and heresy hardened into the name for punishable dissent.
noun · /HAIR-uh-see/
A belief or opinion that contradicts established or officially accepted doctrine.
What it names
The idea a community treats as not merely wrong but forbidden — a marker of where the boundaries of acceptable thought have been drawn and enforced.
Example
Suggesting the flagship product should be discontinued was treated as heresy in the boardroom.
Related idea
Heresy is deviation from within a tradition, which is what makes it dangerous to that tradition; a polemic is an outsider’s open assault, which insiders can more easily dismiss.