epilepsy (n.) Look up epilepsy at Dictionary.com
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.