The word 房顶 is formed by combining two characters: 房 (fáng), meaning "house" or "building", and 顶 (dǐng), meaning "top" or "summit". It is a straightforward compound where the first character defines the object (a building), and the second character specifies the particular part of that object being referred to, its uppermost surface or covering. The formation follows a direct, logical pattern of whole-to-part description, creating a new, concrete concept from two independent, meaningful components.