The same reptile known as a river turtle in illinois is called a cooter in florida. This language phenomenon is classified as

The same reptile known as a river turtle in Illinois is called a cooter in Florida. This language phenomenon is classified as regionalism.

Explanation:

Regionalisms are words, expressions or attributions of meanings whose use is exclusive of a specific geographical area.

In the English language, those words or expressions of a locality or region that are not used in other places because there is an equivalent or they have a different meaning from the original are considered regionalisms.