late 14c., from M.L. sciatica, in sciatica passio "sciatic disease," from fem. of sciaticus "sciatic," from L. ischiadicus "of pain in the hip," from Gk. iskhiadikos, from iskhias (gen. iskhiados) "pain in the hips," from iskhion "hip joint." Sciatic (adj.) is attested from 1540s.
sciatica sci·at·i·ca (sī-āt'ĭ-kə) n. Pain along the sciatic nerve that radiates from the lower back to the buttocks and back of the thigh and is usually caused by a herniated disk of the lumbar region of the spine.