Webster's Revised Unabridged Dictionary · 1913

Epilepsy

Epilepsy , noun

[Latin epilepsia, Greek {not transcribed} a seizure, the “falling sickness,” from {not transcribed} to take besides, seize, attack; 'epi` upon, besides + {not transcribed} to take: compare French épilepsie. Compare Catalepsy.]

(Medicine) The “falling sickness,” so called because the patient falls suddenly to the ground; a disease characterized by paroxysms (or fits) occurring at interval and attended by sudden loss of consciousness, and convulsive motions of the muscles.
falling sickness, — Dunglison