Avariety of nonstandard english spoken by members of a regional, ethnic, or social group is called a(n) idiom overgeneralization dialect colloquialism

dialect(s)

Explanation:

A dialect always stems from a language and has unique pronunciation, a particular form of a language that developed under certain circumstances and  is characteristic to a specific region or  identifies a social group.

English dialects are divided by region:

British Isles dialects

Australasia

The dialects in North America.

Examples, Chicano English comes from Latinos, mostly a mixture between Mexican and American groups

They can understand if communicating with New York Latinos , that  is the reason why a dialect is considered, as speakers of one form of the language can understand speakers of the other.

All languages have dialects since regional and cultural influences are reflected as culture will influence the language in a given space and time.

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