The word 贩毒 is formed by combining two meaningful characters: 贩 (fàn), which carries the core idea of "to sell" or "to traffic", and 毒 (dú), which means "poison" but is used here to mean "drugs" or "narcotics". Their combination is direct and conceptual, placing the action of selling together with the specific, illicit commodity being sold. This creates a single, fused concept that precisely and efficiently denotes the criminal activity of drug trafficking.