平躺 (píng tǎng) literally means 'flat lie' — combining 平 (píng), meaning 'level', 'flat', or 'even', and 躺 (tǎng), meaning 'to lie down'. Together, they describe the specific posture of lying completely flat on one’s back, with the body horizontal and face upward. This term emphasizes alignment and even contact with the surface — unlike general lying down, which could include side-lying or reclining.

It is commonly used in medical, therapeutic, and fitness contexts: doctors may instruct patients to 平躺 for examinations or recovery; yoga or physical therapy guides often specify 平躺 for relaxation poses like Savasana. It also appears in daily life when describing rest positions — for example, after exercise or before sleep — but always implies full back support and intentional stillness. The word carries a neutral, slightly formal tone and is rarely used for animals or casual, unstructured resting.