koiné
Koine refers to a common dialect that develops among speakers of mutually intelligible dialects. This shared dialect often arises in areas with significant trade, migration, or political influence, leading to increased interaction between different groups. As people from various regions come into contact, they tend to simplify their speech, dropping less common or more regional features in favor of a more widely understood form. This process can lead to the formation of a koine, which then serves as a lingua franca or common language for the region.
Historically, koine languages have played a significant role in the spread of culture, religion, and commerce.