'Apennines' originates from Latin, specifically the word 'Apennīnus' (used for the Apennine mountains), where the exact root is uncertain and likely derives from an earlier Italic or pre-Roman local name.

'Apennīnus' in Classical Latin was used to denote the mountain range; this form continued in Medieval Latin as 'Apenninus' and was adopted into English as 'Apennines' to refer to the range across the Italian peninsula.

Initially it referred to the specific mountains described by ancient writers; over time it has continued to denote the entire mountain chain running the length of Italy and is used as the standard geographic name.