'Yāo wéi' literally combines 腰 (yāo), meaning 'waist', and 围 (wéi), meaning 'circumference' or 'girth'. Together, they form the precise medical and everyday term for waist circumference — the measurement taken horizontally around the narrowest part of the torso, usually just above the navel. This measurement is widely used in health assessments to evaluate abdominal fat and associated risks like heart disease or type 2 diabetes.

In daily life, yāo wéi appears on clothing size charts (especially pants and skirts), in fitness tracking apps, and during routine physical exams. It's often reported in centimeters (e.g., 72 cm) and compared against clinical thresholds. Unlike general terms like 'size' or 'fit', yāo wéi specifically denotes a quantitative body measurement — making it essential for accurate health monitoring and garment selection.