contradict

Short definition from Wiktionary

Verb

1. 1
   To deny the truth or validity of (a statement or statements).
2. 2
   To oppose (a person) by denying the truth or pertinence of a given statement.
3. 3
   To be contrary to (something).
4. 4
   To say things that conflict with each other.
5. 5
   To give an order contrary to (another order or wish), oppose (something).
6. 6
   To give an order contrary to one given by (another person), oppose or resist (someone).
7. 7
   To speak against; to forbid.