Contradict
Part of speech: verb
Definition: To speak against; to forbid. To deny the truth of (a statement or statements). To make a statement denying the truth of the statement(s) made by (a person).
Example sentence: A writer may tell me that he thinks man will ultimately become an ostrich. I cannot properly contradict him.
Contravene
Part of speech: verb
Definition: To act contrary to an order, or fail to conform to a regulation.To deny the truth of something.