The word 暗杀 is formed by directly combining two characters: 暗, which means "dark" or "hidden", and 杀, which means "to kill". The concept is created by placing the method or circumstance (暗 - in darkness/secrecy) directly before the core action (杀 - killing). It is a vivid, almost pictorial compound where the first character acts as an adverbial modifier for the second, painting the specific image of a killing carried out covertly from the shadows, thus giving the meaning of "assassinate".