n.1. the entire physical structure of an organism, such as the human body. 2. the physical body as opposed to the mental processes of a human being. See mind–body problem. 3. the trunk or torso of a human or nonhuman animal. 4. the main part of a structure or organ, such as the body of the penis. 5. a discrete anatomical or cytological structure, such as the Barr body (see sex chromatin).