Oblique: Italicized text derived from the Roman version of a font.
OCR: Optical Character Recognition, or the ability of an application to convert scanned text into text that can be edited. Most graphics editing programs now include OCR technology.
Off-color: Paper or ink that does not exactly match the color desired.
Offset Lithography: The type of lithographic printing. In this process the image and nonimage areas are created on the same plate. The areas are separated with chemicals. To print, ink is rubber stamped to the paper.
Opacity: Used to specify how transparent a layer should be, either on its own or in regard to other layers. When color-separating artwork, you can use the Opacity Slide to "pull" more color from the image, thus making color separating artwork easier.
Opaque: Not transparent, among other meanings including to “block out" a specific area of an image or film.
Opaquing: The process of removing pinholes in an image, often performed by screen printers on screens produced by films.
Options bar: This bar is located at the top of the interface underneath the menu bar and changes each time a new tool is selected. The options bar contains choices for configuring and working with the various tools in the toolbox.
Original: The artwork required for printing reproduction. An “original" may mean camera-ready artwork or artwork you acquire for editing and reproduction in a different, usable, form.
Out of Gamut: A color not within the specified color gamut. Often, out of gamut errors occur when using Web colors only to create an image.
Outline Letter: A letter created only with an outline that does not have a solid middle.
Outside Margin: The area outside the margins of a printed page. It is often referred to as the trim margin.
Overlay: Color screens that are layered, and once layered produce additional colors on an image. You can create overlays in Photoshop when creating transparencies for presentations using an overhead projector, adn then use those overlays to enhance the presentation to show changes, without actually changing the slide.
Overset: Text or type that is in excess of the available space in the image. This means that the type in a line exceeds measure allotted for the type.