The Dictionary of Publishing and Printing (3rd edition - 2006) by theguardian (no spaces : ) contains over 8.000 terms which it claims is clearly defined. That may be so, but some of the definition are so concise, that you have to look up other words to find out what it means! Nonetheless, for every word I searched for I found an answer and therefore as a dictionary of publishing and printing it works, and is helpful.
There is also some examples and quotations from magazines to show how the words are used in context. The dictionary also includes a useful supplement at the back. This features: Proof Reading Marks (in tables so you can see what they are and what they mean); Copyright Law in the U.K. (from 1954-94), Copyright Resources (on the internet, websites), lots of U.K. Publishers; list of Books Prizes and Awards; International Book Fairs (which month and where); the Greek alphabet, Common Diacritics, Examples of Different Fonts and other websites related to all aspects of publishing, printing, writing, editing, proof reading etc.
Good Dictionary of Publishing and Printing Terms