(1) The middle portion of the alimentary canal of certain vertebrate animals in which it is continuous with the foregut, thus, starts at the duodenum at the opening of the bile duct, and ends at hindgut
(2) The portion of the embryonic alimentary canal that develops into intestines, particularly the distal portions of the duodenum, jejunum, ileum, cecum, appendix, and the ascending colon and most of the transverse colon of the large intestine
(3) The mesenteron
In adult vertebrates, the midgut primarily serves as the site of digestion and absorption.
Word origin: mid– (middle) + gut