'anergia' originates from Greek, specifically the word 'anergos', where 'an-' meant 'without' and 'ergon' meant 'work'.

'anergos' changed from the Greek word to the medical Latin 'anergia', and eventually became the modern English word 'anergia'.

Initially, it meant 'without work or activity', but over time it evolved into its current meaning of 'lack of energy or inactivity, especially in a medical context'.