In Printing, an assemblage of letters, words, and lines, arranged in order, and disposed into pages by the compositor; from which, by means of ink and the press, sheets are printed. Every form is enclosed in an iron chase, wherein it is firmly locked by a number of wedge-shaped pieces of wood of various sizes. There are two forms required in every sheet, one for each side: and each form consists of more or fewer pages, according to the size of the book. See Printing.