'Apennine' originates from Latin, specifically the word 'Apenninus', and is also attested in Ancient Greek as 'Apenninos', the historical name for the mountain range.

'Apennine' changed from Latin 'Apenninus' (and Greek 'Apenninos') through Medieval/Anglo-Latin and early English forms into the modern English 'Apennine' and the plural 'Apennines'.

Initially it referred specifically to that Italian mountain range; over time the name has retained that geographic meaning and is used both for the range and for individual peaks of that system.