Shālòu (hourglass) is a traditional timekeeping device consisting of two glass bulbs connected by a narrow neck, with fine sand flowing from the upper bulb to the lower one at a steady rate. The word combines 沙 (shā), meaning 'sand', and 漏 (lòu), which historically refers to 'leaking' or 'dripping' — as in water clocks (water 'leaks' through an aperture) — here extended metaphorically to describe the gradual, controlled flow of sand. Though no longer used for practical timekeeping, the shālòu appears frequently in Chinese literature, art, and idioms to symbolize the passage of time, impermanence, or patience.

In modern usage, shālòu often carries poetic or nostalgic connotations. It may appear in educational contexts when teaching historical measurement tools, or in decorative items like desk ornaments and wedding gifts symbolizing enduring love. Unlike digital clocks, it evokes slowness and mindfulness — making it a common visual metaphor in essays, poems, and even mobile app interfaces designed for focus timers.