The word **风云 (fēngyún)** is a **binomial compound** formed by combining two independent, related characters: **风 (fēng)**, meaning "wind," and **云 (yún)**, meaning "cloud." It operates through **metonymy**, where the concrete meteorological phenomena of rapidly changing winds and clouds are used metaphorically to represent **volatile, unpredictable, and momentous situations**—much like "stormy weather" in English signifies turmoil. This figurative meaning is extended to describe major shifts in politics or society (e.g., 风云变幻, "fast-changing events") and to refer to influential figures who shape such times (e.g., 风云人物, "man of the hour"). Thus, its formation follows the common Chinese lexical process of combining two semantically associated nouns to create a new, idiomatic abstract concept.