The phrase "knock on effect" refers to the domino effect of one event leading to a chain reaction of consequences. There are several synonyms that can be used to describe this phenomenon, including a ripple effect, a snowball effect, a chain reaction, a butterfly effect, and a domino effect. Each of these terms essentially refers to the same concept in slightly different ways. A ripple effect emphasizes the gradual spread of an event's influence, like ripples spreading across water. A snowball effect suggests that the consequences of an event become larger and more impactful as they pick up momentum. A butterfly effect emphasizes the notion that small changes can have far-reaching consequences. No matter which synonym you choose, they all describe the interconnectedness of events and the way that one small action can set off a chain reaction of outcomes.