The term "inter-zone" typically refers to the area between two different zones or regions. There are several synonyms for this term, including interstitial, transitional, border, and intermediate. The word interstitial is often used in medical contexts to refer to the spaces between tissues and organs, while transitional is commonly used to describe the period of change between two different phases. Border is a more general term that can refer to the edge or boundary between two areas, while intermediate describes the middle ground between two extremes. No matter which synonym you choose, each word helps to convey the idea of a space that exists in between two established areas or regions.