plural of proof house

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

plural of proof spirit

plural of smoke proof

(typography, now chiefly historical) A temporary print made from a thin coating of carbon deposited on the punch surface by a candle flame, used in evaluating the progress of the design of the punch.

plural of page proof

plural of proof of concept

plural of galley proof

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

(informal, humorous) Incapable of being misused even by the most stupid or careless of users.