malapropism

noun

1. an act or habit of misusing words ridiculously, especially by the confusion of words that are similar in sound.
2. an instance of this, as in “Lead the way and we’ll precede.”

noun

1. the unintentional misuse of a word by confusion with one of similar sound, esp when creating a ridiculous effect, as in I am not under the affluence of alcohol
2. the habit of misusing words in this manner

n.1826, from Mrs. Malaprop, character in Sheridan’s play “The Rivals” (1775), noted for her ridiculous misuse of large words (e.g. “contagious countries” for “contiguous countries”), her name coined from malapropos. A humorous confusion of words that sound vaguely similar, as in “We have just ended our physical year” instead of “We have just ended our fiscal year.”