'atonia' originates from Ancient Greek, specifically the word 'ἀτονία' (atonía), where prefix 'a-' meant 'without' and 'tonos' meant 'tension' or 'tone'.

'atonia' changed from Ancient Greek 'ἀτονία' into Late/Medical Latin 'atonia' and eventually became the modern English medical term 'atonia'.

Initially, it meant 'absence of tension or tone' in a general sense; over time it has been preserved in medical usage to mean 'loss or absence of muscle or organ tone'.