duodenum

noun

du·​o·​de·​num ˌdü-ə-ˈdē-nəm How to pronounce duodenum (audio) du̇-ˈä-də-nəm How to pronounce duodenum (audio)
 also  (ˌ)dyü-
plural duodena ˌdü-ə-ˈdē-nə How to pronounce duodenum (audio)
du̇-ˈä-də-nə
or duodenums
: the first part of the small intestine extending from the pylorus to the jejunum

Word History

Etymology

Middle English, from Medieval Latin, from Latin duodeni twelve each, from duodecim twelve; from its length, about 12 fingers' breadth

First Known Use

14th century, in the meaning defined above

Time Traveler
The first known use of duodenum was in the 14th century

Browse Nearby Words

Cite this Entry

“Duodenum.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/duodenum. Accessed 10 Sep. 2025.

Kids Definition

duodenum

noun
plural duodena -ˈdē-nə How to pronounce duodenum (audio)
-ᵊn-ə
or duodenums
: the first part of the small intestine extending from the opening from the stomach into the small intestine to the jejunum
duodenal adjective

Medical Definition

duodenum

noun
plural duodena -ˈdē-nə, -ᵊn-ə How to pronounce duodenum (audio) or duodenums
: the first, shortest, and widest part of the small intestine that in humans is about 10 inches (25 centimeters) long and that extends from the pylorus to the undersurface of the liver where it descends for a variable distance and receives the bile and pancreatic ducts and then bends to the left and finally upward to join the jejunum near the second lumbar vertebra
duodenal adjective

More from Merriam-Webster on duodenum

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!