A regional language is a language spoken in a region of a sovereign state, whether it be a small area, a federated state or province or some wider area.

Internationally, for the purposes of the European Charter for Regional or Minority Languages, "regional or minority languages" means languages that are:

Recognition of regional or minority languages must not be confused with recognition as an official language.

In some cases, a regional language may be closely related to the state's main language or official language. For example:

In other cases, a regional language may be very different from the state's main language or official language. For example:

An official language of a country may also be spoken as a regional language in a region of a neighbouring country. For example: