Ap"o*plex`y (ăp"&osl;*pl&ebreve;ks`&ybreve;), n. [OE. poplexye, LL. poplexia, apoplexia, fr. Gr. 'apoplhxi`a, fr. 'apoplh`ssein to cripple by a stroke; 'apo` from + plh`ssein to strike: cf. F. apoplexie. See Plague.] (Med.) Sudden diminution or loss of consciousness, sensation, and voluntary motion, usually caused by pressure on the brain.

&fist; The term is now usually limited to cerebral apoplexy, or loss of consciousness due to effusion of blood or other lesion within the substance of the brain; but it is sometimes extended to denote an effusion of blood into the substance of any organ; as, apoplexy of the lung.

• (Medical) Sudden diminution or loss of consciousness, sensation, and voluntary motion, usually caused by pressure on the brain.