'Appalachian' originates from Spanish, specifically the name 'Apalachee', recorded by early Spanish explorers and referring to a Native American people/place in the southeastern present-day United States.

'Appalachian' changed from the Spanish term 'Apalachee' and the variant forms used by French explorers (e.g. 'Appalaches'), and eventually became the English form 'Appalachian' used for the mountains, region, and people.

Initially, it referred to the name of a tribe or place ('Apalachee'); over time it came to denote the mountain range, the surrounding region, and characteristics or people from that region ('of Appalachia').