背光 (bèi guāng) literally means 'back light' — '背' meaning 'back' or 'against', and '光' meaning 'light'. As an adjective, it describes a situation where the main subject is positioned between the viewer and a light source (e.g., the sun or a lamp), causing its front to appear dark or silhouetted while the background is brightly lit. This term is frequently used in photography, cinematography, and wildlife observation.

In everyday language, 背光 often appears in descriptions of animals or people seen against bright backgrounds — for instance, birds flying across the sky at sunset, or a cat sitting by a sunlit window with its face in shadow. It’s also common in technical contexts like screen displays (e.g., 'backlit display'), though that usage typically involves the noun form 背光 (bèi guāng) as a modifier. Unlike the English word 'backlit', which can be both verb and adjective, 背光 functions almost exclusively as an attributive or predicative adjective in Chinese.