1A traditional custom or idea adhered to although shown to be unreasonable.
- ‘‘A young priest once corrected an old priest for saying mumpsimus instead of sumpsimus in the first prayer after Communion in the Latin Mass. ‘Son,’ said the old priest, ‘I've been saying mumpsimus for thirty years and I'm not going to change my old mumpsimus for your new sumpsimus.'’’
- 1.1A person who obstinately adheres to old customs or ideas in spite of evidence that they are wrong or unreasonable.‘At one time or another, all journalists run the risk of being mumpsimuses - if there is such a word.’
- ‘These dealers and collectors are real mumpsimuses about it, just like those who misuse the word ‘stub’.’
- ‘We've all got a bit of a mumpsimus in us in some way shape or form don't we?’
- ‘I just don't see anything cute or cuddly about a mumpsimus or a bigot; I've spent too much of my life having to deal with real people like that.’
- ‘It isn't nice to tar us with the same brush and make us appear to be mumpsimuses like yourself.’
Mid 16th century erroneously for Latin sumpsimus in quod in ore sumpsimus ‘which we have taken into the mouth’ (from the Eucharist), in allusion to the story of an illiterate priest who, when corrected for reading quod in ore mumpsimus, replied ‘I will not change my old mumpsimus for your new sumpsimus’.