Complex sentence: An exonym or xenonym is an external name for a geographical place, group of people, or language/dialect: a common name used only outside the place, group or linguistic community in question, usually for historical reasons.
Split into simpler sentences: An exonym or xenonym is an external name for a geographical place, or a group of people, or a language or dialect. It is a common name used only outside the place, group, or linguistic community in question, usually for historical reasons.