What does "apoplexy" mean?

Apoplexy: Sudden diminution or loss of consciousness, sensation, and voluntary motion, usually caused by pressure on the brain. Note: 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.