Proof

The word proof can mean:

• originally, a test assessing the validity or quality of something.

• a rigorous, compelling argument, including:
  • a logical argument or a mathematical proof (see also proof theory)
  • a legal proof
  • a large accumulation of scientific evidence

• a photograph, print or page layout presented as an example for proofreading or approval

• alcoholic proof, a measure of how much alcohol is in a beverage

• Proof, a play by David Auburn

• Proof, a film by Jocelyn Moorhouse

• a Proof coin is a coin made especially for coin collectors, usually distinguished by being struck twice (or at a higher pressure) and often with polished fields and frosted devices.