1. One who adheres to an old habit in spite of clear evidence that it is
wrong.
2. An old custom obstinately kept although it is known to be in error.
For Latin: sumpsimus "we have taken"
From the story of an English priest who upon being
corrected for saying in the Mass "quod in ore mumpsimus" retorted "I will
not change my old mumpsimus for your new sumpsimus"