The word 内衣 is formed by directly combining two meaningful characters: 内 (nèi), which means "inner" or "inside", and 衣 (yī), which means "clothing" or "garment". The concept is constructed by placing the modifier 内 before the general category 衣, creating a literal and intuitive compound meaning "inner clothing", which naturally refers to garments worn beneath outer layers, such as underwear.