The word 牛皮癣 is formed by combining 牛 (cow), 皮 (skin), and 癣 (skin disease). The term literally means "cow skin disease", where 牛皮 (cowhide) metaphorically describes the thickened, rough texture of the affected skin, and 癣 specifies it as a skin condition. Thus, the word directly references the physical resemblance of the diseased skin to cowhide.