AA Abbreviation for author's alteration. Author's alterations are changes made to a job after it has already been sent to a printer for production. If you (the customer) make changes to your original file, these are AAs and the printer can charge you for making them. If, however, the errors are attributable to the printer, these are PEs (printer's errors) and you don't pay for correcting them. See PE's.

Absorption The property that causes paper to absorb liquids or vapors in contact with it. In optics, the partial suppression of light through a transparent or translucent material.

Accordion fold In binding, a term used for two or more parallel folds that open like an accordion

Acrobat Adobe's Portable Document Format, referred to as PDF.

Additive primaries In color reproduction, red, green, and blue (RGB). When lights of these colors are added together, they produce the sensation of white light.

Addressability The number of spots per inch (spi) or centimeter (spc). We also use the term "dpi" (dots per inch) as a measure for addressability. Spi is used for output devices, not input devices, where the equivalent term would be sampling count, that is measured in units of samples per image length, width, or area (not samples per inch).

Against the grain Folding or feeding paper at right angles to the grain direction of the paper. Also called crossgrain.

Airbrush A small pressure gun shaped like a pencil that sprays watercolor pigment. Used to correct and obtain tone or graduated tone effects. In offset platemaking, a pumice used to remove unwanted areas. In electronic imaging, a retouching technique. This technique disappeared as film disappeared and is now done with image editing programs.

Alkaline paper Paper made with a synthetic alkaline size and an alkaline filler such as calcium carbonate that gives the paper many times the life (200 years) of acid-sized papers (40-50 years).

AM/FM screening This is an issue to discuss with your printer as to which screen option is more appropriate for your job. The advantage of FM screening is that moiré patterns are no longer an issue.

AM (Amplitude Modulation) screening (see FM) Traditional halftone screening, as opposed to FM (Frequency Modulated) screening, has dots of variable size with equal spacing between dot centers. Hybrid screen combines AM and FM screening. See halftone.

Analog color proof Off-press color proof made from separation films or files.

Anilox inking In flexography, two-roll inking system with a smooth fountain roll that transfers inks to an etched metal or ceramic-coated metal roll with cells of fixed size and depth that transfer the ink to the printing plate. Now also being offered with new offset lithographic presses. Also used in keyless offset.

Anti-halation backing In photography, coating applied to the back of film to prevent halation.

Anti-offset or set-off spray In printing, dry spray of finely powdered starch used on press to prevent wet ink from transferring from the top of one sheet to the bottom of the next sheet. This also separates the sheets on a micro level so oxygen can react with the ink to enhance ink drying.

Antique finish A term describing the textured surface, usually on book and cover papers, that has a naturally rough finish to it.

Aperture In photography, lens opening or lens stop expressed as an f/number such as f/22.

Apochromatic In photography, color-corrected lenses that focus the three colors blue, green, and red, in the same plane.

APR (Automatic Picture Replacement) The automatic replacement of a low-resolution image by a high-resolution image. See OPI.

Art All illustration material used in preparing a job for printing. May also refer to drawings and charts specifically.

Ascender That part of a lowercase letter that rises above the main body, as in "b."

ASCII (American Standard Code for Information Interchange) A standard means of representing text as numerical data.