The story
Latin ablative of duodecimus (“twelfth”) (from duodecim 'twelve', from duo 'two' + decem 'ten')
Etymology from Wiktionary, CC BY-SA 4.0.
duodecimo
Today it means: A size of paper, so called because it is originally made by folding and cutting a single sheet from a printing press into 12 leaves; (5 by 7¾ inches): 6.5 to 7.5 inches high, approximately 4.5 inches wide. Full definition →