jejunum The portion of the mammalian small intestine that follows the duodenum and precedes the ileum. The surface area of the lining of the jejunum is greatly increased by numerous small outgrowths (see villus). This facilitates the absorption of digested material, which is the prime function of the jejunum.

je·ju·num / jiˈjoōnəm/ • n. [in sing.] Anat. the part of the small intestine between the duodenum and ileum.DERIVATIVES: je·ju·nal / ˈjoōnl/ adj.

jejunum The part of the small intestine next beyond the duodenum, and leading to the ileum. Its lining has an enormous surface area, by virtue of folds, projections (villi), and microvilli on the villi. Enzyme secretion and digestion, started in the stomach, continue here, and absorption of the products begins — of glucose and amino acids into blood capillaries and of fats into lymph capillaries (lacteals).

Stuart Judge

jejunum Part of the small intestine, between the duodenum and the ileum; see gastro‐intestinal tract.

jejunum (ji-joo-nŭm) n. part of the small intestine. It comprises about two-fifths of the whole small intestine and connects the duodenum to the ileum.
—jejunal adj.