What word does your mother always say?
late 14c., from Medieval Latin duodenum digitorium "space of twelve digits," from Latin duodeni "twelve each." Coined by Gerard of Cremona (d.1187), who translated "Canon Avicennae," a loan-translation of Greek dodekadaktylon, literally "twelve fingers long," the intestine part so called by Greek physician Herophilus (c.353-280 B.C.E.) for its length, about equal to the breadth of twelve fingers.
duodenum du·o·de·num (dōō'ə-dē'nəm, dyōō'-, dōō-ŏd'n-əm, dyōō-)
n. pl. du·o·de·nums or du·o·de·na (dōō'ə-dē'nə, dyōō'-, dōō-ŏd'n-ə, dyōō-)
The beginning portion of the small intestine, starting at the lower end of the stomach and extending to the jejunum.