The word 房屋 is formed by combining two characters, 房 and 屋, which each independently carry the core meaning of "house" or "building". They are near-synonyms, and their combination is not grammatical but conceptual, merging to create a single, more general, and slightly more formal term that encompasses the idea of a house or building as a physical structure. This pairing reinforces and broadens the meaning, resulting in a compound that refers to buildings or housing in a comprehensive sense.