What is an imprint in publishing terms?

Answer

The imprint is the "brand name" under which a book is published. Most major publishers have at least a few imprints. Some of these imprints are organized as subsidiaries, or "companies within a company," with their own editorial staffs, release lists, etc. Others are strictly brand names slapped on a book purchased and edited somewhere in the corporation.

According to Wikipedia, Random House, the world's largest English-language trade book publisher, has more than 50 imprints.