Wiktionary
a. (context printing English) Before going to press.
Wikipedia
Prepress is the term used in the printing and publishing industries for the processes and procedures that occur between the creation of a print layout and the final printing. The prepress procedure includes the manufacture of a printing plate, image carrier or form, ready for mounting on a printing press, as well as the adjustment of images and texts or the creation of a high-quality print file. In today's prepress shop, the form of delivery from the customer is usually electronic, either a PDF or application files created from such programs as Scribus, Adobe InDesign or QuarkXPress.
Usage examples of "prepress".
Since then, he has worked as a prepress technician in the printing industry and later moved on to creating editorial illustrations full time for a national computer magazine.