Exonym, endonym

An exonym or xenonym is an external name for a geographical place, a group of people, an individual person, or a language or dialect. It is a common name used only outside the place, group, or linguistic community in question.

An endonym or autonym is an internal name for a geographical place, a group of people, or a language or dialect. It is a common name used only inside the place, group, or linguistic community in question; it is their name for themselves, their homeland, or their language.

All four of the terms (exonym, endonym, autonym and xenonym) are from the Greek root word ónoma (ὄνομα), ‘name’, from Proto-Indo-European *h₁nómn̥. The prefixes are from the Greek éndon (ἔνδον), ‘within’; autós (αὐτός), ‘self’; éxō (ἔξω), ‘out’; and xénos (ξένος), ‘foreign’.

As pertains to geographical features, the United Nations Group of Experts on Geographical Names defines:

• Endonym: Name of a geographical feature in an official or well-established language occurring in that area where the feature is located.
• Exonym: Name used in a specific language for a geographical feature situated outside the area where that language is spoken, and differing in its form from the name used in an official or well-established language of that area where the geographical feature is located.