'擦边球' (cā biān qiú) literally means 'grazing-the-edge ball' — a term borrowed from table tennis, where a ball that just touches the edge of the table is still in play. Figuratively, it refers to an action or decision that deliberately skirts the boundary of acceptability, legality, or ethics: technically permitted but morally questionable or socially risky.

The word combines 擦 (cā, 'to brush/graze'), 边 (biān, 'edge/border'), and 球 (qiú, 'ball'). It’s commonly used in discussions about business practices, social behavior, or policy implementation — for instance, exploiting loopholes without outright breaking rules. While neutral in form, it often carries a mildly critical or cautionary tone, implying awareness of potential consequences if the 'edge' is crossed.