The word 窃听 is formed by directly combining the meaning of its two component characters: 窃, which means "to steal" or "secretly", and 听, which means "to listen" or "hear". Together, they create a vivid conceptual image of "stealing listening" or "listening in secret", which perfectly encapsulates the act of covert eavesdropping or wiretapping. The formation is a straightforward semantic fusion where the action of the second character is performed in the manner described by the first.