imprimatur

thumb|An imprimi potest, a [[nihil obstat, and an imprimatur (by the Archbishop of Boston) on a book published by Random House in 1953. The book in question is the English translation by Louis J. Gallagher of De Christiana expeditione apud Sinas by Matteo Ricci. and Nicolas Trigault.]]

An imprimatur (sometimes abbreviated as impr., from Latin, "let it be printed") is a declaration authorizing publication of a book. The term is also applied loosely to any mark of approval or endorsement. The imprimatur rule in the Catholic Church effectively dates from the dawn of printing, and is first seen in the printing and publishing centres of Germany and Venice; many secular states or cities began to require registration or approval of published works around the same time, and in some countries such restrictions still continue, though the collapse of the Soviet bloc has reduced their number.