'legitimately' originates from Latin, specifically the word 'legitimus,' where 'leg-' meant 'law.' 'Claim' originates from Latin, specifically the word 'clamare,' meaning 'to call out or declare.'

'legitimus' transformed into the Old French word 'legitime,' and eventually became the modern English word 'legitimate.' 'Clamare' transformed into the Old French word 'clamer,' and eventually became the modern English word 'claim.'

Initially, 'legitimus' meant 'lawful,' and 'clamare' meant 'to call out.' Over time, 'legitimately-claimed' evolved to mean 'rightfully asserted.'