(printing) A page of proofed text; a sheet used to make corrections, emendations etc. before being printed for use. / (photography) A contact print.

plural of proof sheet

(printing, historical) The last proof for correction before sending to press. / (printing, historical) A proof taken on a press, especially to show impression, margins, colour, etc.

plural of press proof

plural of proof spirit

plural of proof of concept

Of a book, film, etc.: guaranteed to succeed even if it receives unfavourable reviews.

plural of galley proof

(idiomatic) A real-life person or thing which demonstrates the validity of a hypothesis.

plural of smoke proof