The phrase "within the body" refers to something that is located inside the physical structure of an organism. Synonyms for this phrase include "internally," "inside," "inwardly," and "intraorganismal." These terms describe the location and position of things that are situated within the body, such as organs, tissues, cells, or molecules. "Intrinsic" is another word that can be used to describe things that are essential to the body's functioning and are located within its structure. These synonyms are helpful in communicating about the anatomy and physiology of living organisms, and can be used in medical and scientific contexts to describe various aspects of the body's internal workings.