Malapropism n. : A grotesque misuse of a word; a word so used.

Example:
Can you help me to compare AND contrast a pun and Malapropism?

Taxonomy
malapropism, Act 2, commiserate, rynda, writers, Mrs. Malaprop, character, language, substitution, free encyclopedia, ism, Scene II, Washington, D.C., New Scientist, comic effect, catastrophe, The Simpsons, utterances.

Defination from the web:
malapropism (also called a Dogberryism, acyrologia, Morna-ism,or "Rickyism") is the substitution of a word for a word with a similar sound, in ... The terms malapropism and the earlier variant malaprop come from Richard Brinsley Sheridan's 1775 play The Rivals, and in particular ...