sacred cow

WordReference Random House Learner's Dictionary of American English © 2025

ˈsa•cred ˈcow, n. [countable]

1. someone or something thought to be important and therefore not to be criticized or questioned.

WordReference Random House Unabridged Dictionary of American English © 2025

sa′cred cow′, 

1. an individual, organization, institution, etc., considered to be exempt from criticism or questioning.

• in reference to the traditional inviolability of the cow among Hindus 1905–10

Collins Concise English Dictionary © HarperCollins Publishers::

sacred cow noun

1. a person, institution, custom, etc, unreasonably held to be beyond criticism

Etymology: alluding to the Hindu belief that cattle are sacred