The word **底片 (dǐpiàn)**, meaning "photographic film" or "negative," is formed through semantic compounding, where the meaning of the whole is derived from the combined meanings of its two constituent characters: **底 (dǐ)**, meaning "base," "bottom," or "foundation," and **片 (piàn)**, meaning "a flat slice," "sheet," or "piece." Together, they literally describe the object as the "base sheet"—a transparent sheet that serves as the foundational carrier for the light-sensitive emulsion layer which, after exposure and development, holds the inverted (negative) image from which positive prints are made.