‘光束’ (guāng shù) literally combines 光 (guāng), meaning 'light', and 束 (shù), meaning 'bundle' or 'bunch'. Together, they form a compound noun meaning 'beam of light' — a narrow, focused stream of light traveling in a particular direction. It emphasizes the shape and coherence of light, like sunlight piercing through clouds or a laser pointer’s line.

This word is commonly used in scientific, descriptive, or poetic contexts — for example, when discussing optics, photography lighting, or natural phenomena like sunbeams in a forest. Unlike the more general word 光 (guāng), which just means 'light', 光束 highlights directionality and concentration. It appears frequently in textbooks, nature writing, and technical descriptions, but rarely in casual speech.