'apologise' originates from Late Latin/Medieval Latin 'apologiare' and Old French influences, ultimately from Greek 'apologia' meaning 'a speech in defense'.

'apologise' changed from Medieval Latin and Old French forms (via Late Latin 'apologiare' and Old French 'apologiser') and entered Middle English as 'apologisen' before becoming modern English 'apologise'.

Initially it meant 'to make a formal speech in defence' (from Greek 'apologia'), but over time it evolved into the modern primary sense 'to express regret' (and secondarily 'to defend or justify').