Source : Webster's Revised Unabridged Dictionary (1913)

Malapropism \Mal"a*prop*ism\, n. [From Mrs. Malaprop, a
   character in Sheridan's drama, `` The Rivals,'' who makes
   amusing blunders in her use of words. See {Malapropos}.]
   A grotesque misuse of a word; a word so used.

Source : WordNet®

malapropism
     n : the unintentional misuse of a word by confusion with one
         that sounds similar [syn: {malaprop}]