Uncoated Paper
Paper that has not been coated with clay. Also called offset paper.

Undercolor Removal
The removing of cyan, magenta, or yellow from a heavily colored image to limit the total amount of ink being applied to that image to avoid potential production problems.

Up
A term used to describe how many similar sheets can be produced on a larger sheet. "Two up" or "three up" means printing the identical piece twice or three times on each sheet.

Upright
A term given to books bound on the longer dimension.

UV Coating
A liquid coating applied to the printed sheet and bonded and cured on press with ultraviolet (UV) light.  This shiny coating yields a tough, almost unscratchable surface that is extremely durable.