mumpsimus
- A person who obstinately adheres to an old, erroneous custom or belief even after being shown the correct version; also, the erroneous notion or habit itself.
In a sentence
- No amount of evidence could shake his mumpsimus; he continued to pronounce the word incorrectly simply because he always had.
- The editor warned that insisting on the outmoded rule was a classic mumpsimus, long abandoned by every major style guide.
Usage note. Mumpsimus can refer to either the stubborn person or the stubborn error itself, so clarify which sense you mean; its contrast term 'sumpsimus' (the correct form pedantically insisted upon) is far rarer but occasionally appears in linguistic discussions.
Where it comes from
English mumpsimus · entered English 16th c.
The word originates from a story—possibly apocryphal—recorded by Erasmus in the 16th century, in which an illiterate English priest had for years incorrectly read 'mumpsimus' in the Mass instead of the correct Latin 'sumpsimus' (meaning 'we have taken'), and when corrected, refused to change his habit. The tale was widely repeated, and the word entered English in the 16th century as a term for stubborn adherence to error. It appears in some standard dictionaries including Merriam-Webster.