The word 岩石 is formed through the semantic combination of two characters, each carrying a core meaning related to "rock". The first character, 岩, specifically denotes a cliff, crag, or a large, prominent rock formation. The second character, 石, is the general, fundamental term for stone or rock. By joining them, the compound creates a more precise and reinforced concept than either character alone, specifically meaning "rock" in the geological sense, a solid, natural aggregate of minerals. This formation exemplifies a common Chinese word-building method where two characters with similar or related meanings are combined to define a clear, unified concept.