The Chinese word "大气层" (dàqìcéng), meaning "atmosphere," is a compound noun formed through semantic combination. It consists of three characters: "大" (dà, meaning "big" or "great"), "气" (qì, meaning "air" or "gas"), and "层" (céng, meaning "layer" or "stratum"). The term is constructed logically where "大气" (dàqì) itself means "atmosphere" or "air," and the addition of "层" (céng) specifies it as a layered structure, thus together forming the precise scientific term for the spherical layers of gases enveloping a celestial body. This formation follows a common Chinese word-creation pattern of modifying a root concept ("大气") with a descriptive classifier ("层") to create a more specific, compound technical term.