Meaning

noun a system of hills in Britain that extend from the Scottish border in the north to the Trent River in the south; forms the watershed for English rivers

originUsually connected to the Italian Apennines, originally borrowed from Latin Apenninus by Latin scribes and subsequently losing its initial A by rebracketing or aphesis. Alternatively, possibly derived directly from a Celtic language; by surface analysis, Proto-Brythonic *penn (“(hill) top, head”) plus -ine.

Etymology from Wiktionary, CC BY-SA 3.0