The Chinese word **污渍** (wūzì), meaning "stain" or "blemish," is a **compound noun** formed through semantic combination. Its first character, **污** (wū), carries the core meaning of "dirt," "filth," or "something unclean." The second character, **渍** (zì), specifically means a "spot" or "stain" left by a liquid, often implying something soaked in or留下的痕迹 (liúxià de hénjì). When combined, they create a precise and vivid term where **污** describes the *nature* of the substance (dirty) and **渍** describes its *form* (a marked spot), resulting in the clear concept of a "dirty mark," i.e., a stain.