'apatheia' originates from Ancient Greek, specifically the word 'apatheia', where 'a-' meant 'without' and 'pathos' meant 'suffering, passion'.

'apatheia' changed from Ancient Greek 'apatheia' into Late/Medieval Latin and was later borrowed into English (via scholarly and philosophical Latin/French usage) as 'apatheia'.

Initially, it meant 'freedom from passion' as a Stoic ideal; over time it broadened in English to include the modern sense of 'absence of feeling or indifference'.