Bible Dictionaries
Duodecimo

Webster's Dictionary

(1):

(a.) Having twelve leaves to a sheet; as, a duodecimo from, book, leaf, size, etc.

(2):

(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¡.

Bibliography Information
Webster, Noah. Entry for 'Duodecimo'. Noah Webster's American Dictionary. https://www.studylight.org/​dictionaries/​eng/​web/​d/duodecimo.html. 1828.