(Law) A license to print or publish a book, paper, etc.; also, in countries subjected to the censorship of the press, approval of that which is published.
(R. C. Ch.) Permission granted from a designated eccliastical authority to publish a book or other document; required by church law for Catholics, especially ecclesiastics, who wish to publish.
Hence: Official approval for some proposed activity; as, a contract this large needs the imprimatur of the legal department.