OCR (Optical Character Recognition) - a special kind of scanner which provides a means of reading printed characters on documents and converting them into digital codes that can be read into a computer as actual text rather than just a picture.

Offprint - a run-on or reprint of an article first published in a magazine or journal.

Offset printing - A lithographic method of printing in which the ink is first transferred from the image to an offset blanket and then to the stock which may be paper, card, metal or other material.

Onion skin - a translucent lightweight paper used in air mail stationery.

Opacity - term used to describe the degree to which paper will show print through.

Optical centre - a point above the true centre of the page which will not appear 'low' as the geometric centre does.

Outline - a typeface in which the characters are formed with only the outline defined rather than from solid strokes.

Outsert -  A printed element which is usually stitched to the outside of a magazine cover.

Overprinting - printing over an area already printed. Used to emphasise changes or alterations.

Overs - additional paper required to compensate for spoilage in printing. Also used to refer to a quantity produced above the number of copies ordered.

Ozalid - a trade name to describe a method of copying page proofs from paper or film.