Irrefutable evidence is PROOF that cannot be denied or argued against. It is the strongest form of evidence and is often used in legal proceedings. The term 'irrefutable evidence' can be broken down into two crossword solutions: 'PROOF' (5 letters) and 'smokinggun' (10 letters). The term 'PROOF' refers to evidence that is strong enough to convince a person of something, while 'smokinggun' is a metaphor for something that provides undeniable evidence of guilt or wrongdoing.