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.


  • Poise
    A unit for measuring viscosity, equal to one dyne per second per square centimeter; one gm/cm/sec.
  • Poisson's ratio
    Absolute value of the ratio of transverse strain to axial strain resulting from a uniformly applied axial stress below the proportional limit of the material.
  • Polar adhesion
    Adhesion to a surface that has polarity such as wood, paper and cloth.
  • Polar solvent
    A solvent with oxygen in their molecules such as water, alcohol, ketone, esters, or other solvent having a high dielectric content.
  • Polishing
    The name of a defect that occurs in matte ink, when the gloss of a print can be increased by rubbing.
  • Pollution
    Undesirable foreign materials, usually waste, in the air, water or on the land.
  • Polyacrylonitrile (PAN)
    A synthetic fiber used as a base material or precursor in the manufacture of certain carbon fibers.
  • Polyamide
    Alternate spelling for polyimide.
  • Polybasic acid
    Maleic, succinic, and phthalic acid having two or more carboxyl groups per molecule.
  • Polycarbonate (PC)
    A thermoplastic material derived from the reaction of aromatic dihydroxy compounds with carbonic acid with high impact strength, low water absorption, heat and moisture resistant, and good electrical and optical properties.
  • Polychloroprene
    Chemical name for neoprene.
  • Polychrome
    A multi-colored image or print.
  • Polydomes (polyester dome)
    Spherically formed element in polyester circuit material to provide tactile response in electronic switches.
  • Polyester (UP)
    A thermosetting plastic derived from unsaturated ester polymer dissolved in a monomer such as styrene used in the production of film and fiber, strong, extremely tough, adversely affected by UV light and chlorinated solvents, but resistance to most other solvents, acids, and salts.
  • Polyethylene (PE)
    A thermoplastic produced by the direct polymerization of ethylene at high temperatures and pressures; process variations and the lowering of temperature and pressure create high, medium, and low density materials.
  • Polyethylene terephthalate (PET)
    A thermoplastic formed by reaction of either purified terephthalic acid or dimethyl terephthalate with ethylene glycol, used for synthetic fiber and film, blow molded, and thermoformed parts.
  • Polyhydric alcohol
    Alcohols such as glycol and glycerol containing more than one C-OH group per molecule.
  • Polyimide (PI)
    A thermoset or thermoplastic formed by the reaction of a dibasic acid with a diamine to form a salt and then a polymeric amide; polyamide resins are nylons. (Sometimes spelled polyamide).
  • Polymer
    A long chain molecular structure compound formed by a reaction between monomers and or oligimers, having functional groups that permit their combination to proceed to high molecular weights under suitable conditions by polymerization or polycondensation. (Polymers can be plastic, elastomers, liquids, or gums).
  • Polymerization
    A chemical reaction initiated by a catalyst, heat, light, or water causing monomers and/or oligimers to linked together to form a polymer.
  • Polyolefin (PO)
    A thermoplastic (polyethylene or polypropylene) that is based on polymers of olefin.
  • Polypropylene (PP)
    A thermoplastic material similar to polyethylene with a higher molecular weight resulting from polymerization of propylene gas; the lightest of the thermoplastics.
  • Polystyrene (PS)
    A thermoplastic material derived from the polymerization of styrene that is clear and exhibits high stiffness, good dimensional stability, low specific gravity and excellent electrical properties.
  • Polyvinyl acetate (PVAc)
    A vinyl polymer or copolymer mainly used in the manufacturing of adhesives and emulsions.
  • Polyvinyl alcohol (PVOH)
    A thermoplastic that is produced from full or partial hydrolysis of vinyl ester such as vinyl acetate resulting in the replacement of some or all of the acetyl groups with hydroxyl groups.