Which term refers to a body position lying face up?

The term that refers to a body position lying face up is "supine." In medical terminology, this position is commonly used to describe a patient lying flat on their back, which is important for various procedures, examinations, and assessments in clinical settings.

In contrast to other terms, "prone" refers to a position where an individual lies face down, which is opposite to supine. "Lateral" describes a position where a person lies on their side, and "recumbent" generally indicates a position of lying down but can refer to both supine and prone positions without specifying which way the face is oriented. Thus, "supine" specifically denotes lying face up, making it the correct choice in this context.