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

noun. A book composed of pages of this size.

noun. 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.

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

noun. 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°.

adjective. Having twelve leaves to a sheet

noun. 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°.

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 A size of paper, so called because it is originally made by folding and cutting a single sheet from a printing press into 12 leaves; (5 by 7¾ inches): 6.5 to 7.5 inches high, approximately 4.5 inches wide.

noun. A sheet or page of that size

noun. A book having pages of that size

"_Inset_, the portion of a sheet cut off and inserted in folding certain sizes, such as duodecimo, &c. (see Fig. 4)."

andiron  black-letter  bullet-hole  closely-printed  closely-written  

12mo  12°  D  twelvemo