[n] the act of validating; finding or testing the truth of something
[n] a trial photographic print from a negative
[n] (printing) a trial impression made to check for errors
[n] (logic or mathematics) a formal series of statements showing that if one thing is true something else necessarily follows from it
[n] a measure of alcoholic strength expressed as an integer twice the percentage of alcohol present (by volume)
[v] make resistant, as to water, sound, errors, etc.
[v] activate by mixing with water and sometimes sugar or milk; "proof yeast"
[v] read for errors
[v] make or take a proof of, such as a photographic negative, an etching, or typeset