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.
This name was sometimes used as a personal name, and was borne by a few early saints
, including a Roman soldier martyred with Nereus in the 1st century.