Yours, Etc.: Origins and Uses of 8 Sign-Offs
late 14c., "sudden fit of paralysis and dizziness," from Old French apoplexie or directly from Late Latin apoplexia, from Greek apoplexia, from apoplessein "to strike down and incapacitate," from apo- "off" (see apo-), in this case probably an intensive prefix, + plessein "hit" (cf. plague (n.), also with a root sense of "stricken"). The Latin translation, sideratio, means "disease caused by a constellation."
apoplexy ap·o·plex·y (āp'ə-plěk'sē)
Sudden impairment of neurological function, especially from a cerebral hemorrhage; a stroke.
An effusion of blood into a tissue or organ.