'ataraxy' originates from Greek, specifically the word 'ataraxia' (Greek ἀταραξία), where the prefix 'a-' meant 'not' and 'tarachē'/'tarassein' related to 'disturbance' or 'to throw into disorder'.

'ataraxy' entered English via Latin/Medieval Latin 'ataraxia' (and through French 'ataraxie' in some usages), with the English form 'ataraxy' developing as a rare variant of 'ataraxia'.

Initially in Greek it meant 'absence of disturbance' or 'freedom from trouble'; in English it evolved to denote 'tranquility, calmness, or imperturbability' often in a philosophical or literary sense.