What term describes a person lying face up?

The term that describes a person lying face up is "supine." This term is commonly used in medical and emergency settings to indicate a specific body position that is important for assessing or providing care to a patient. When a patient is positioned supine, it allows for unobstructed access to the chest for procedures like CPR, and it facilitates the examination of vital signs and other assessments.

In contrast, "prone" refers to a position where the person lies face down. "Vertical" denotes an upright position, which does not apply to lying down. "Recumbent" can refer to a person lying down in general but does not specify the face-up orientation, making "supine" the most precise term for someone who is specifically on their back. Understanding these terms is crucial for effective communication in emergency medical situations.