Dictionary:

refutation

  (rĕf'yʊ-tā'shən) also refutal (rĭ-fyūt'l)

1. The act of refuting.
2. Something, such as an argument, that refutes someone or something.

The noun has 3 meanings:

Meaning #1: the speech act of answering an attack on your assertions
  Synonyms: defense, defence

Meaning #2: any evidence that helps to establish the falsity of something
  Synonyms: disproof, falsification

Meaning #3: the act of determining that something is false
  Synonyms: falsification, falsifying, disproof