The word 污染 (wūrǎn) is formed by combining two characters, each contributing a crucial layer of meaning to create the modern concept of "pollution". The first character, 污 (wū), inherently means "dirty", "filthy", or "foul", establishing the core quality of impurity. The second character, 染 (rǎn), means "to dye", "to stain", or "to catch (a disease)", introducing the dynamic action of spreading that impurity and causing contamination. Thus, the compound visually and conceptually merges the state of being "foul" (污) with the process of "staining or spreading" (染) to perfectly encapsulate the idea of polluting or pollution, where a contaminant taints and spreads through a clean environment.