sciatica n.

"disease characterized by pain in the sciatic nerve," c. 1400, from Medieval Latin sciatica, in sciatica passio "sciatic disease," fem. of sciaticus "sciatic," a corruption of Latin ischiadicus "of pain in the hip," from Greek iskhiadikos, from iskhias (genitive iskhiados) "pain in the hips," from iskhion "hip joint, socket in which the thigh-bone turns." Compare euiskhios "with beautiful hips" (Hellenistic poetry). Related: Sciatical.