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: 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
