mumpsimus

[muhmp-suh-muh s]
noun, plural mump·si·mus·es for 2.
  1. adherence to or persistence in an erroneous use of language, memorization, practice, belief, etc., out of habit or obstinacy (opposed to sumpsimus).
  2. a person who persists in a mistaken expression or practice (opposed to sumpsimus).

Origin of mumpsimus

1520–30; from a story, which perhaps originated with Erasmus, of an illiterate priest who said mumpsimus rather than sūmpsimus (1st plural perfect indicative of Latin sūmere to pick up; see consume) while reciting the liturgy, and refused to change the word when corrected
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for mumpsimus

Historical Examples of mumpsimus