'Hillingdon' may mean the hill of a man, Hille – or of a woman, Hilda.
It appears in the Domesday Book of 1086 as Hillendone. In Anglo-Saxon place names -don usually means a hill, here probably Hillingdon Hill, which rises near Uxbridge. From the mid-1930s to the mid-1950s the station was called Hillingdon (Swakeleys), after a nearby junction on Western Avenue. The once local name now covers a whole London borough.