The phrase "lies prone" refers to lying face down. Some synonyms for this phrase include lying prone, lying flat, lying prostrate, and lying face forward. Other ways to describe this position include lying belly-down, lying facedown, or lying on one's stomach. These synonyms can be useful in a variety of contexts, such as medical reports, descriptions of body positions during exercise, or police reports. Understanding synonyms for common phrases can help writers convey their ideas more effectively and avoid repetition.