refutation refutation /ˌrɛfjuːˈteɪʃən/

noun

1. The act of determining that something is false  ( disproof , falsification , falsifying , refutal , refutation )
   the act of determining that something is false
   
2. Any evidence that helps to establish the falsity of something  ( disproof , falsification , refutation )
   any evidence that helps to establish the falsity of something
   
3. The speech act of answering an attack on your assertions  ( defence [Canadian, British] , refutation , defense [American] )
   the speech act of answering an attack on your assertions
    His refutation of the charges was short and persuasive
   his refutation of the charges was short and persuasive
    In defense he said the other man started it
   in defense he said the other man started it