Glossary Of Terms

The SGIA Glossary of Terms serves as an excellent industry terminology resource. It is the language by which we all communicate, without it universal understanding would be impossible. Language and our ideas about how it is interpreted change rapidly. SGIA is aware of this and continues its effort to keep our constituents well informed about changes to the increasingly complex industry terminology. The definitions are for general reference only. Usage may vary between companies, individuals, or national and country customs. The information presented is as accurate as the authors and editors can ascertain and SGIA assumes no responsibility for the use of information presented herein.


  • Activated sludge treatment
    A water effluent waste treatment employing forced air to accelerate biodegradation process.
  • Activator
    (1) A chemical used to accelerate a reaction or increase chemical activity in another material; (2) In photography, a high pH solution that allows diffusion of the developer into the film emulsion for development of the image.
  • Active component (active devise)
    A part or element in an electronic device that controls current or voltage to produce gain, impede or resist flow, or provide switching action in a printed circuit.
  • Active substrate
    A substrate or base for an integrated circuit component where parts of the substrate display voltage or current control to accomplish gain, impedance, or switching.
  • Activity
    In thermodynamics, the active concentration of a free ion in solution.
  • Actuation force
    (1) The amount of pressure necessary to close a membrane switch, measured in grams; (2) The force required to collapse the walls of a rubber keypad, metal, or polyester dome.
  • Acutance
    The acute details of shape or sharpness of the edge of a printed line or dot.
  • Acute
    A toxic effect that results from a short term exposure to a very high concentration of a toxic substance.
  • Acute effect
    The adverse effects that normally are evident immediately, or shortly after exposure to a hazardous material, generally no longer than 14 days.
  • Adaptive compression
    A type of compression software commonly used to back up files. The method of compression will change with the type of file, and is not recommended for photographic images because it may destroy original data.
  • Additive
    A substance added in small amounts to another to improve desirable qualities or suppress undesirable properties, or otherwise changes the composition to a predetermined state.
  • Additive color matching
    Process that can specify colors in terms of the three numbers representing the amounts of the three primary lights added together to make a match. (The amounts of the three primaries, expressed in numerical form for each primary and describing the new color, are known as the tri-stimulus values of that color).
  • Additive lamps
    A medium pressure mercury vapor UV lamp (arc or microwave) that has small amount of metal halide added to the mercury. (These materials will emit their characteristic wavelengths in addition to the mercury emissions).
  • Additive primary colors
    Red, green, and light blue; when all additive primaries are combined at 100% intensity, white light is produced; combining at varying intensities produces a gamut of different colors.
  • Addressable resolution
    The highest resolution of a printer, scanner, etc. in working with an image, also refer to optical resolution and interpolation.
  • Adherend
    Any item that is attached to another item or surface by an adhesive.
  • Adhering liquid
    A solvent used for attaching lacquer-filled knife-cut stencil film to the screen mesh, usually a blend of lacquer-type solvents.
  • Adhesion
    The molecular force of attraction between unlike materials; being united or attached, by a mechanical, chemically, or reactive bond between surfaces causing them to stick together; (adhesion to a smooth surface may rely on polar adhesion).
  • Adhesion buildup
    An increase in the peel adhesion value of pressure sensitive tape after it has been allowed to dwell on the applied surface.
  • Adhesion shear
    A measure of the time required to slide a standard area (as of a decal) from a standard flat surface in a direction parallel to the surface.
  • Adhesion test
    Any of a variety of test methods used to determine adequate bonding of ink or coating to a substrate.
  • Adhesive (glue) (cermet) (gum)
    A substance capable of holding materials together by surface attachment.
  • Adhesive bleed (ooze)
    Adhesive exudation from pressure sensitive stock before or after processing to finished product, as a result of cold flow or clamp pressure.
  • Adhesive residue
    (1) Adhesive deposit remaining on substrate due to cohesive failure when a pressure sensitive material is removed; (2) Adhesive remaining on water-applied decal after application to a surface.
  • Adjacency effect
    (1) Property of the eye that causes the same color to look different when surrounded by or adjacent to other colors, such as a color will appear darker when surrounded by a lighter color, or lighter when surrounded by a darker color; (2) Alterations in exposure densities within a silver halide film emulsion that occur during processing at the conjunction areas of differing densities.