Malapropism

Definition:
Malapropism is the mistaken use of a word in place of a similar-sounding one, often with unintentionally amusing effect. It often occurs in ordinary speech. Malapropism is also called a malaprop or dogberryism. Malapropism reveals that the English language is complex because it is easy to mistake two words for each other.
Literary example:
Officer Dogberry said, "Our watch, sir, have indeed comprehended two auspicious persons" (apprehended two suspicious persons)