duodenum
noun
du·o·de·num
ˌdü-ə-ˈdē-nəm 
du̇-ˈä-də-nəm
du̇-ˈä-də-nəm
also (ˌ)dyü-
plural duodena
ˌdü-ə-ˈdē-nə
du̇-ˈä-də-nə
or duodenums
: the first part of the small intestine extending from the pylorus to the jejunum
Cite this Entry
“Duodenum.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/duodenum. Accessed 31 Oct. 2025.
Copy CitationKids Definition
duodenum
noun
du·o·de·num
ˌd(y)ü-ə-ˈdē-nəm
d(y)u̇-ˈäd-ᵊn-əm
d(y)u̇-ˈäd-ᵊn-əm
plural duodena
-ˈdē-nə
-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
Medical Definition
duodenum
noun
du·o·de·num
ˌd(y)ü-ə-ˈdē-nəm
d(y)u̇-ˈäd-ᵊn-əm
d(y)u̇-ˈäd-ᵊn-əm
plural duodena
-ˈdē-nə, -ᵊn-ə
or duodenums
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
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