Is it ensure, insure, or assure?
1570s, from Middle French epilepsie (16c.), from Late Latin epilepsia, from Greek epilepsia "seizure," from epi "upon" (see epi-) + lepsis "seizure," from leps-, future stem of lambanein "take hold of, grasp" (see analemma).
Earlier was epilencie (late 14c.), from Middle French epilence, with form influenced by pestilence. The native name was falling sickness.
epilepsy ep·i·lep·sy (ěp'ə-lěp'sē)
Any of various neurological disorders characterized by sudden, recurring attacks of motor, sensory, or psychic malfunction with or without loss of consciousness or convulsive seizures.