The Chinese word 急于 (jíyú) is a compound formed through grammaticalization, where the core adjective 急 (jí), meaning "urgent" or "anxious," is combined with the prepositional particle 于 (yú), which historically means "at," "in," or "to." In this fixed structure, 于 functions as a grammatical marker that links the state of urgency directly to a subsequent action or goal, transforming the adjective into a predicate meaning "to be anxious to" or "to be in a hurry to." Thus, the formation creates a standard complement construction where 于 introduces the object of one's urgency (e.g., 急于离开, "anxious to leave"), making it a concise and idiomatic way to express eagerness or impatience toward a specific action.