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°(paper printing) A size of paper, so called because it is originally made by folding and cutting a single sheet from a printing press into 12 leaves; (5 by 7¾ inches): 6.5 to 7.5 inches high, approximately 4.5 inches wide.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