Someone's rectum is the bottom end of the tube down which waste food passes out of their body. rectums recta the lowest part of your bowels. End segment of the large intestine (see digestion) in which feces accumulate just prior to discharge. It is 5-6 in. (13-15 cm) long and lined with mucous membrane. One set of muscles separates it from the anal canal; another shortens it to expel feces. The rectal walls distend as feces enter, which stimulates the urge for defecation
the terminal portion of the intestinal tract extending from the colon to the anus