The word 额头 (étóu), meaning "forehead", is a compound noun formed through a common Chinese morphological process where the core semantic character 额 (é), which independently means "forehead" or "brow", is combined with the general, often suffix-like character 头 (tóu), meaning "head". This structure follows a "specific + general" pattern, where 头 acts as a categorical marker that specifies the body part context, thereby softening or making the term more colloquial compared to the standalone, more technical-sounding 额. The result is a disyllabic word that is phonetically balanced and typical of modern Mandarin vocabulary.