When it comes to multiplying or describing something that has a quadruple effect or component, the word "four-fold" comes to mind. However, there are other potential synonyms that can be just as effective in describing a fourfold increase or component. For instance, "quadruple" can be used to describe the fourfold nature of something. Additionally, "four times" or "four times as much" can be used to indicate a fourfold increase in a quantity or value. "Multiplicative" and "quadripartite" are also potential synonyms that can be used to describe a four-fold component of something. Whether you use "four-fold" or one of these synonyms, it is important to make sure the meaning is clear and understood by your audience.