The Chinese word 摩擦 (mócā), meaning "friction" or "to rub", is a semantic compound formed by combining two characters with closely related meanings. The first character, 摩 (mó), carries the core meaning of "to rub" or "to grind", while the second, 擦 (cā), means "to wipe" or "to scrape". When paired, their meanings converge and reinforce each other, creating a single, more vivid concept that describes the physical action and resulting resistance of one surface moving against another. This is a common pattern in Chinese word formation known as a coordinative compound, where two elements of similar meaning are combined to express a nuanced or more general idea.