Impressive Images offers this comprehensive list of graphic design terms and printing terminology.
Artwork: The original copy, type, illustrations, and photographs to be used in the printing job. Synonym: art.
Base Art / Base Mechanical: Copy pasted on the mounting board of a mechanical, the opposite of overlay art.
Blueline / Blueprint: Creating a photographic proof, prepress, using stripped negatives with all the colors printed with blue ink on white paper.
CMYK: The abbreviation of the four print process colors: cyan, magenta, yellow and key (black).
Matchprint: Multiple piece of contact proofing pieced together and laminated. Most accurate proofing method.
Number of Pages: How many pages does your book or brochure have? This is different from how many sheets of paper. For an "apples to apples" and easy to quote them it is best to always deal in page count and not sheet count for a given item.
Trim Size Folded: Final size of printed piect after it is folded.
Text Stock: Paper used for printing.
Cover Stock: Similar to a cover sheet. The outside paper layer of the printed piece.
Cover Ink: Ink used for cover portion of printed piece.
Camera Ready Art: Document artwork ready to be photographed and printed - this is the final version. Color should be separated and a composite of the separations included as a pre-press printing guide.
Half Tones: Basic black and white image reproduced as dots.
Blueline: Contact proof from the film used for verification. Rough sketch of camera ready art that is cheap to print.
Color Key: Contact proof made from the film.
Watermark: Translucent logo barely visible in paper created during manufacturing by embossing from a print roll while the paper is still wet.