What is the term for someone or something that triggers a process or event?

The term "catalyst" refers to a substance or agent that stimulates or accelerates a process or event without being consumed or altered in the process. In various contexts, including chemistry and broader applications such as social change or project management, a catalyst is something that initiates change or expedites a reaction. For instance, in chemistry, a catalyst may lower the activation energy required for a reaction, allowing it to proceed more quickly or at lower temperatures. Similarly, in social movements or organizational change, a person or event can serve as a catalyst by inspiring action or facilitating progress.

In contrast, the other terms have distinct meanings that do not relate to triggering processes or events. Coerce implies forcing someone to act in a certain way, coddle suggests pampering or overprotecting someone, and coalesce means to come together to form one mass or whole. None of these terms convey the idea of initiating or accelerating a process, which solidifies "catalyst" as the correct answer.