duodecimoyoudaoicibaDictYouDict[duodecimo 词源字典]
1650s, from Latin in duodecimo (folded) "in a twelfth" of a sheet, from ablative of duodecimus "twelfth," from duodecim (see dozen). Often abbreviated 12mo.; a book in which each page is the twelfth part of the printer's sheet.[duodecimo etymology, duodecimo origin, 英语词源]