From the Greek Αχιλλευς (Achilleus) which is of unknown meaning, perhaps derived from Greek αχος (achos) "pain" or else from the name of the Achelous River. This was the name of a warrior in Greek legend, one of the central characters in Homer's 'Iliad'. The bravest of the Greek heroes in the war against the Trojans, he was eventually killed by an arrow to his heel, the only vulnerable part of his body.