Doublure. The lined and decorated inside face of boards on fine bindings. When so lined the cover is said to be "double."
Dummy. 1. A book made up of blank leaves to show style of binding and grade of workmanship. 2. A piece of leather or cloth mounted on a board to show exact size and lettering of a periodical.
Duodecimo. Book printed on paper folded into twelve leaves. Generally written 12mo. Loosely applied to books from six to eight inches high.
Dutch metal. An imitation of gold leaf which soon tarnishes.
Edges cut. A book which has all edges trimmed smooth.
Edges gilt. All edges trimmed smooth and gilded.
Edges opened. A book which has the folds of leaves cut by hand with a paper knife, has its edges opened.
Edges rolled. The edges of the covers are marked with a roll.
Edges trimmed. Edges cut somewhat, but not enough to cut all the folds.
Edges uncut. Uncut edges have not been trimmed in any way, though they may have been opened with a paper knife.