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n. The size (5 by 7 3/4 inches) of book pages formed by folding single sheets from a printing press into 12 leaves each.

n. A book composed of pages of this size.

n. A size of paper, so called because it is originally made by folding and cutting a single sheet from a printing press into 12 leaves; (5 by 7¾ inches): 6.5 to 7.5 inches high, approximately 4.5 inches wide.

n. A sheet or page of that size

n. A book having pages of that size

adj. Having twelve leaves to a sheet

n. A book consisting of sheets each of which is folded into twelve leaves; hence, indicating, more or less definitely, a size of a book; -- usually written 12mo or 12°.

n. A size of page usually measuring, in the United States, about 5⅛ inches in width and 7⅔ inches in length, when the leaf is uncut, and corresponding to crown octavo of British publishers.

n. A book composed of sheets which, when folded, form twelve leaves of this size.

n. In music, the interval of a twelfth.

Consisting of sheets folded into twelve leaves; having leaves or pages measuring about 5⅛ by 7⅔ inches. Often written 12mo or 12°.

"I recently picked up a copy of In Art or Instruction, a limited duodecimo-sized edition published in 1969 as a greeting to friends of Harcourt, Brace & World Inc. on the occasion of its fiftieth year."

12mo    twelvemo    12°    D   

quarto    vellum-bound    black-letter    closely-printed    memento