'apoplexy' originates from Greek, specifically the word 'ἀποπληξία (apoplēxía)', where 'ἀπο-' ('apo-') meant 'away' and 'πλήξις/πλήσσω' (root related to 'plēx/plex') meant 'a striking/blow (to strike)'.

'apoplexy' passed into Late Latin as 'apoplexia', then into Medieval Latin/Old French and Middle English as 'apoplexie'/'apoplexia', eventually becoming the modern English word 'apoplexy'.

Initially, it meant 'a striking away' or 'a sudden striking (attack)', referring to a sudden physical seizure; over time it evolved into the more specific medical meaning of 'stroke' and additionally developed a figurative sense of 'violent anger'.