mumpsimus

A priestly typo became a permanent insult. In the old Eucharistic phrase quod in ore sumpsimus, the respectable Latin verb meant “we have taken,” but one stubborn celebrant kept saying mumpsimus instead—and then kept saying it even after being corrected. That kind of pigheadedness was so memorable that English turned it into a noun for someone who clings to an error as if it were sacred doctrine. It’s a cousin to all those Latin take-with-me words like assume, consume, and resume, except here the “taking” goes badly wrong. The joke is deliciously human: once the wrong form has survived embarrassment, it can become more durable than the truth.