Acid-free Paper
Paper made from pulp containing little or no acid so that it resists deterioration from age. Also called alkaline paper, archival paper, neutral pH paper, permanent paper and thesis paper.

Accordion Fold
A bindery term for two or more parallel folds which open like an accordion. 

Additive Color
Color produced by light falling onto a surface, as compared to subtractive color. The additive primary colors are red, green and blue (RGB).

Against the Grain
Against the grain is running a sheet of paper through the press at right angles (perpendicular) to the direction of the grain of the paper. When a piece is printed against the grain it can make the paper feel thicker, however it is not optimal for both press operation and registration of the 4 color process inks. Sometimes called cross grain.

A defect that is caused by a graphic file which does not have enough resolution to reproduce image detail and causes visible jagged lines along the image edges.

At the proofing stage, changes that the client requests to be made concerning original art provided. Also called Author's Alterations, or AAs.  AAs are usually an additional cost to the client.

Aqueous Coating
Coating in a water base and applied like ink by a printing press to protect and enhance the printing underneath.

In printing terms, art means all original copy, including type, photos and illustrations, intended for printing. Also called Customer Originals.

Any part of a lower case letter extending above the x-height. For example, the upper half of the vertical in the letters b or h.