 | Offset | | Set-off. A defect characterized by the partial transference of ink from a freshly printed surface to an adjacent surface as that of another sheet of paper. |
| Offset Printing | | A process of indirect printing in which an impression of type or a design on a flat plate is printed on a rubber blanketed cylinder from which it is impressed. |
| Olefins | | A group of unsaturated hydrocarbons of the general formula CnH2n and named after the corresponding paraffins by the addition of "ene" or "ylene" to the stem. Examples are ethylene and propylene. |
| Oozing | | A "squeezing out" of the adhesive from under the backing, occurring when the tape is in roll form, the edges of the roll become tacky. |
| Opacity | | That property of a paper or film which prevents "show through" of dark printing on or in contact with the backside of the sheet. This is opposite of transparency. |
| Opaque Ink | | An ink that conceals all color beneath it. |
| Orange Peel | | A pebbled appearance of a surface. Small, rounded hills and valleys caused by uneven liquid flow in coating or printing. |
| Orientation | | The alignment of the crystalline structure in polymeric materials so as to produce a highly uniform structure. Can be accomplished by cold drawing or stretching during fabrication. |
| Outgas | | Vaporization of a solid or liquid under heat. Outgassing can occur in some plastics and insufficiently dried plants, resulting in adhesive failure of films applied over them. |
| Overcoating | | In extrusion coating, the practice of extruding a web beyond the edge of the substrate. |
| Overlaminating | | Application of clear film to a graphic for the purpose of protection or to enhance the graphic quality. |
| Overlap | | Wrap-around labeling of a container in which one end of the label overlaps the other. |
| Oxidation | | The chemical reaction involving the process of combining with oxygen to form an oxide; the deterioration of an adhesive film due to atmospheric exposure; the breakdown of a hot melt adhesive due to prolonged heating and oxide formation. |