noun

• (countable) An effort, process, or operation designed to establish or discover a fact or truth; an act of testing; a test; a trial.
  "I need proof of your unconditional love. Lend me some dough."
• (uncountable) The degree of evidence which convinces the mind of any truth or fact, and produces belief; a test by facts or arguments which induce, or tend to induce, certainty of the judgment; conclusive evidence; demonstration.
  "I'll have some proof."
• (obsolete) Experience of something.
  "But the chaste damzell, that had never priefe / Of such malengine and fine forgerye, / Did easely beleeve her strong extremitye."
• (uncountable, obsolete) Firmness of mind; stability not to be shaken.

adj

• (of alcoholic liquors) Being of a certain standard as to alcohol content.
  "60% proof liquor"

verb

• (transitive, intransitive, colloquial) To proofread.
• (transitive) To make resistant, especially to water.
• (transitive, firearms) To test-fire with a load considerably more powerful than the firearm in question's rated maximum chamber pressure, in order to establish the firearm's ability to withstand pressures well in excess of those expected in service without bursting.
• (transitive, baking) To allow (yeast-containing dough) to rise, especially after it has been shaped
  "dough proofing"