A shí yīng zhōng (quartz clock) is a timekeeping device that uses the regular vibrations of a quartz crystal to regulate its movement. The word combines three characters: shí (stone), yīng (crystal or 'English'—here a phonetic loan for 'quartz'), and zhōng (clock). Though yīng literally means 'English', in this compound it’s used purely for its sound to approximate the English word 'quartz', making 石英 a transliteration meaning 'quartz'—a common pattern in modern Chinese scientific terminology.

Quartz clocks are widely used in homes, offices, and schools due to their accuracy, affordability, and low maintenance compared to mechanical clocks. They typically run on batteries and display time digitally or with analog hands. While not as precise as atomic clocks, they’re far more accurate than traditional pendulum or spring-driven clocks—losing only about one second per month under normal conditions.