Mumpsimus

A mumpsimus is an action by a person who adheres to a routine, idea, custom, set of beliefs, or a certain use of language that has been shown to be unreasonable or incorrect. For example, a person may continue to mispronounce and misunderstand the phrase all intents and purposes as all intensive purposes, even after being corrected. The term mumpsimus may also refer to the person who performs the action.

Mumpsimus has been defined as a "traditional custom obstinately adhered to however unreasonable it may be", as well as "someone who obstinately clings to an error, bad habit or prejudice, even after the foible has been exposed and the person humiliated; also, any error, bad habit, or prejudice clung to in this fashion". In other words, mumpsimus can describe the behavior, as well as the person doing it. Garner's Modern American Usage says the word could describe George W. Bush because of his persistent habit of pronouncing "nuclear" as /noo-kyə-lər/ ("nucular") instead of the standard /noo-klee-ər/, despite the error being widely reported.

The term originates from an apocryphal story about a poorly educated Catholic priest saying Latin mass who, reciting the postcommunion prayer Quod ore sumpsimus, Domine ["What we have received in the mouth, Lord"], instead of sumpsimus ["we have received"] says the non-word mumpsimus. After being made aware of his mistake, he nevertheless persisted with his erroneous version, either from arrogance, ignorance or stubborn force of habit or from refusing to believe he was mistaken.

The story was told by Desiderius Erasmus (1466–1536) in a letter he wrote in August 1516 to Henry Bullock. Erasmus used it as an analogy with those who refused to accept that Novum Instrumentum omne, his edition of the Greek New Testament, corrected errors in the Latin Vulgate. The English diplomat Richard Pace (1482–1536) included a variant in his 1517 work De Fructu qui ex Doctrina Percipitur, where the priest was English and had been saying mumpsimus for thirty years when corrected. While Pace's book (written in Latin) is credited by the first edition of the Oxford English Dictionary as the origin of "mumpsimus", Pace acknowledged his borrowing in a 1517 letter to Erasmus. "Mumpsimus and sumpsimus" became proverbial among Protestants in the early English Reformation.

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