What It Sounds Like (MUMP-si-mus)
Never seen this word before? What does its sound and shape suggest to you? For me, it's all about that first puffy syllable—I can't help picturing clown cheeks. A mumpsimus smile, for instance, would widen the face and make it look preternatuarlly full. A mumpsimus fish? Well, here's one now!
What It Actually Means
As usual, my playful response to this word is wide (pun intended) of the mark! A noun, mumpsimus has a fascinating history. The Dean of St. Paul's Cathedral in London told the story, in 1517, of a medieval monk who persistently said a phrase in the Latin Eucharist wrongly: instead of “quod in ore sumpsimus," he would always say, “quod in ore mumpsimus”. Now sumpsimus is Latin for “we have taken” (the full phrase means “which we have taken into the mouth”), but mumpsimus is just a malapropism. When his superiors tried to correct his mistake, our good father is said to have replied that he wasn't about to learn a new trick after 40 years. “I will not change my old mumpsimus for your new sumpsimus”.
Which is how the word has come to apply to a notion or idea that is obstinately clung to despite it's being totally unreasonable. You know, the way some folks insist on the mumpsimus that a woman's place is behind the stove! The word can also be used for a person who holds onto such a misguided proposition.
Where It Comes From
The story of that stubborn monk may actually be much older than the 16th century. Some think it's an anecdote borrowd from Erasmus and told in the middle ages. Naturally, part of its pedigree goes back to the Latin sumpsimus, but the contrast suggested between it and its nonsensical counterpart gained real momentum when Henry VIII gave a speech in which he advocated compromise: "Some," he said, "be too stiff in their old mumpsimus, others be too busy and curious in their sumpsimus." Hey, if it was good enough for His Higness, shouldn't we bring back this delicious coinage— it's much too fun to say to stop...
Now Go Out There And USE it!