What term describes an act or event that makes something happen?

The term that describes an act or event that makes something happen is "cause." In the context of causality, a cause is something that produces an effect or brings about a change. It is essential in understanding the relationship between actions or occurrences and their outcomes.

For example, if you water a plant (the cause), it will grow (the effect). The cause is what initiates a process or leads to a particular result. This fundamental concept is prevalent in various disciplines, including science, philosophy, and everyday reasoning.

In contrast, terms like "effect," "action," and "event" describe different aspects of this relationship. "Effect" refers to the result of the cause; "action" signifies a deed or effort performed; and "event" denotes an occurrence or happening. While these terms are related to the concept of causality, they do not specifically define what initiates or brings about a change like "cause" does.