Exonym
A name used by outsiders, differing from the name used where the thing named is.
UNGEGN defines an exonym as a name used in a specific language for a geographical feature situated outside the area where that language is widely spoken, and differing in form from the name used there: English Warsaw for Polish Warszawa, German Mailand for Italian Milano.
Applied to languages — again, a conventional extension rather than UNGEGN’s own definition — an exonym is what outsiders call a language. Cornish, Manx and Hawaiian are English exonyms; Kernewek, Gaelg and ʻŌlelo Hawaiʻi are the endonyms.
An exonym is not automatically wrong, and the UN recommends restraint rather than abolition in international usage. But some exonyms carry the history of who was doing the naming, which is why a profile gives both and leads with the endonym where one is known.