internal organ, viscus - a main organ that is situated inside the body

hindgut - the caudal part of the alimentary canal in vertebrate embryos

small intestine - the longest part of the alimentary canal; where digestion is completed

large intestine - beginning with the cecum and ending with the rectum; includes the cecum and the colon and the rectum; extracts moisture from food residues which are later excreted as feces

abdomen, belly, stomach, venter - the region of the body of a vertebrate between the thorax and the pelvis