'Achilleas' originates from Greek, specifically the name 'Ἀχιλλεύς' (Achilleus), where 'ἄχος' meant 'pain' or 'grief'.

'Ἀχιλλεύς' transformed into the Latin 'Achilles', and eventually became the modern English name 'Achilleas'.

Initially, it referred to a legendary hero, and this meaning has largely remained the same in modern usage.