'Aeacus' originates from Greek mythology, specifically the name 'Aiakos', where 'Aiakos' was a legendary king known for his fairness and justice.

'Aiakos' was adopted into Latin as 'Aeacus', and eventually became the modern English name 'Aeacus'.

Initially, it referred to a specific mythological figure, and this meaning has largely remained the same in modern usage.