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
We are not going to change our old 'mumpsimus' for anybody's new 'sumpsimus.'Res Judicat
Mr. Beckford called the beast, or reptile, a mumpsimus (sic).Recollections of the late William Beckford
Henry Venn Lansdown
Mumpsimus, mump′si-mus, n. an error to which one clings after it has been thoroughly exposed.