ileum /il″ē·əm/ pl. ilea [L, intestine] , the lower-third distal portion of the small intestine, extending from the jejunum to the cecum. Internally it has a few small circular folds and numerous clusters of lymphatic tissues. It ends in the right iliac fossa, opening into the medial side of the large intestine. See also ileocecal valve. −ileal, ileac, adj.
