'关节' (guān jié) literally combines '关' (guān), meaning 'gate' or 'passage', and '节' (jié), meaning 'joint', 'knot', or 'segment'. Together, they refer to the anatomical joints—the movable connections between bones where movement occurs, such as elbows, knees, shoulders, and fingers. The term emphasizes both structural linkage and functional mobility, reflecting traditional Chinese understanding of the body as an interconnected system.

This word is used exclusively in medical, biological, and everyday health-related contexts—not for mechanical or abstract 'joints'. It appears frequently in discussions about pain ('关节痛'), injury ('关节扭伤'), aging ('关节退化'), and physical activity ('保护关节'). Unlike English 'joint', it never means a place of business (e.g., slang for a bar) or a shared action (e.g., 'joint effort'); those meanings use other terms like '场所' or '共同'.