The word "咳嗽" is formed by combining two characters, each constructed as a phonosemantic compound. "咳" incorporates the mouth radical (口) to indicate meaning related to the mouth or sound, and the component "亥" to approximate pronunciation. "嗽" similarly uses the mouth radical (口) for meaning and "欶" for sound. Together, they create a disyllabic term representing the act of coughing.