du·o·dec·i·mo \ˌ ̷ ̷ ̷ ̷ˈdesəˌmō\noun (-s) Etymology: Latin, abl. of duodecimus twelfth, from duodecim twelve 1.: twelvemo — symbol D; see book tables 2.[modification of Italian duodecima, from feminine of duodecimo twelfth, from Latin duodecimus, from duodecim twelve]: the musical interval of a twelfth