The Chinese word 床垫 (chuángdiàn) for "mattress" is a compound noun formed through semantic combination. It consists of two meaningful characters: 床 (chuáng), which means "bed", and 垫 (diàn), which means "cushion" or "pad". When combined, the word follows a modifier-head structure common in Chinese, where the first element 床 specifies the category (something for a bed), and the second element 垫 defines the object's function (a cushioning item), thereby creating the precise meaning of a "bed cushion" or mattress.