What is Imprimatur?

Legal Definition
An imprimatur (from Latin, "let it be printed") is, in the proper sense, a declaration authorizing publication of a book. The term is also applied loosely to any mark of approval or endorsement.
-- Wikipedia
Legal Definition
"Let it be printed.". An authorization for a document to be printed. Used in the context of approval by a religious body or other censoring authority.
Legal Definition
A license or allowance to one to print.

2. At one time, before a book could be printed in England, it was requisite that a permission should be obtained that permission was called an imprimatur. In some countries where the press is liable to censure, an imprimatur is required.
-- Bouviers Law Dictionary
Legal Definition
Lat. Let it be printed. A license or allowance, granted by the constituted authorities, giving permission to print and publish a book. This allowance was formerly necessary, in England, before any book could lawfully be printed, and in sonfe other countries is stlll required.
-- Black's Law Dictionary
Legal Definition
A government license to publish a book.
-- Ballentine's Law Dictionary