twelvemo

[twelv-moh] /ˈtwɛlv moʊ/
noun, plural twelvemos, adjective
1.
Origin
1810-20; twelve + -mo
British Dictionary definitions for twelvemo

twelvemo

/ˈtwɛlvməʊ/
noun (pl) -mos
1.
(bookbinding) another word for duodecimo