The word 内裤 is formed by combining two characters: 内 (nèi), meaning "inside" or "inner", and 裤 (kù), meaning "pants" or "trousers". It is a direct and logical compound where the first character describes the location or purpose, and the second character names the object. Thus, the term literally means "inner pants", which clearly and functionally denotes the garment worn as underwear beneath outer clothing.