Strong emergence is a term used to describe a phenomenon where a higher level of complexity or organization causes a completely new property to emerge that cannot be explained solely by the sum of its parts. There are several synonyms that can be used to describe strong emergence, including irreducibility, unpredictability, novelty, and non-compositionality. These terms all share the common idea that strong emergence points to a fundamental gap in our understanding of how complex systems work. They suggest that we need to develop new frameworks or approaches to study these phenomena, rather than trying to explain them using reductionist or mechanistic models.