How Many People You Know Who Are Guilty of ‘Mumpsimus’?
The word mumpsimus refers to the tendency to misuse words even if one is corrected as to their meaning, spelling, pronunciation, or whatever else embodies the mistaken use.
Allegedly, the word comes from the story about an illiterate priest who continued to mispronounce the liturgy even after corrected. When the priest was corrected for reading quod in ore mumpsimus, he replied, "I will not change my old mumpsimus for your new sumpsimus" (from the Eucharist, "which we have taken into the mouth," sumpsimus="we have taken").
Mumpsimus is also now used to denigrate people whom the observer believes are adhering to ideas or beliefs that are erroneous, i.e., a pejorative term.