Source : Webster's Revised Unabridged Dictionary (1913)

Duodenum \Du`o*de"num\, n. [NL., fr. duodeni twelve each: cf. F.
   duodenum. So called because its length is about twelve
   fingers' breadth.] (Anat.)
   The part of the small intestines between the stomach and the
   jejunum. See Illust. of Digestive apparatus, under
   {Digestive}.

Source : WordNet®

duodenum
     n : the part of the small intestine between the stomach and the
         jejunum
     [also: {duonas} (pl), {duona} (pl)]