OA of Register
When two sheet passes on a press are misaligned.

OBC
Outside back cover

Oblong
A term used to describe printed books, catalogs etc., that are bound on their shorter side; also referred to as album bound.

OFC
Outside front cover.

Off-shore Paper
Any papers made outside the US and Canada.

Offset Printing
Printing technique that transfers ink from a plate to a blanket to paper instead of directly from plate to paper.

Offset Lithographing
Indirect printing method in which the inked image on the press-plate is first printed onto a rubber blanket, then in turn offsets the inked impression on to the sheet of paper.

Opacity
(1) Characteristic of paper or other substrate that prevents printing on one side from showing through the other side. (2) Characteristic of ink that prevents the substrate from showing through.

Orphan
A line of type on its own at the top or bottom of a page.

Overhang Cover
A cover of a book that extends over the trimmed signatures it contains.

Overlay
A transparent sheet placed over artwork, in register with the work it covers; this is used to call out other color components of the work, instructions or corrections.

Overlay Proof
A process of proof making with the color separations individually exposed to light sensitive film. This film is then set in registration with a piece of white paper in the background.

Overprint
Any printing that is done on an area that has already been printed. Also called surprint.

Overrun
Surplus of copies printed.

Overset
Type that is set in excess of the allotted space.