pansypoo's personal rant page.

mumpsimus n. 1. adherence to or persistence in the erroneous use of language, memorization, practice, belief, etc., out of habit or obstinacy (opposed to sumpsimus). 2. a person who persists in a mistaken expression or practice(opposed to sumpsimus). [1520-30; from a story, which perh. originated with Erasmus, of an illiterate priest who said mumpsimus rather than sumpsimus (... some Latin stuff here ...) while reciting the liturgy, and refused to change the word when corrected]

from a Random House unabridged.
Believe it or not, I was checking the spelling of Munch "The Scream" dude and this was four entries earlier.
 

you NEVER stop with the word you want.
i also found my favorite word so far by reading the dictionary-contumacious.