Which term indicates a position that is lying on the back?

The term that indicates a position lying on the back is "supine." In medical terminology, supine specifically refers to a person positioned face upward on their back. This position is commonly used in various medical examinations and procedures because it allows for easy access to the anterior (front) parts of the body.

In contrast, the term "prone" refers to lying face downward, which is the opposite position of supine. The terms "medial" and "lateral" describe positions on the body in relation to the midline; medial means closer to the midline, while lateral means further away from the midline. Thus, these terms do not pertain to lying positions. Understanding these definitions is essential for effective communication in medical settings and helps in providing clear instructions for positioning patients.