The word 传染 (chuánrǎn) is formed by combining two conceptual actions into a single, vivid image of disease spread. The first character, 传, means "to transmit" or "to pass on", establishing the idea of movement from one agent to another. The second character, 染, means "to dye" or "to catch (a color/disease)", powerfully evoking the image of a stain or contamination taking hold. Together, they create a compound that conceptually paints the process of a pathogen or influence being passed from a source and then actively staining or permeating a new host.