The gastrointestinal tract (digestive tract, digestional tract, GI tract, GIT, gut, or alimentary canal) is an organ system within humans and other animals which takes in food, digests it to extract and absorb energy and nutrients, and expels the remaining waste as feces.
The mouth, esophagus, stomach and intestines are part of the gastrointestinal tract.
Gastrointestinal is an adjective meaning of or pertaining to the stomach and intestines.
A tract is a collection of related anatomic structures or a series of connected body organs