'Agamemnon' originates from Ancient Greek, specifically the word 'Ἀγαμέμνων', where 'ἀγα-' meant 'very' and 'μέμνων' meant 'resolute' or 'steadfast'.

'Ἀγαμέμνων' transformed into the Latin word 'Agamemnon', and eventually became the modern English word 'Agamemnon'.

Initially, it meant 'very steadfast', and this meaning has largely remained the same in modern usage.