The Collaborative International Dictionary of English v.0.48:

Sciatica \Sci*at"i*ca\, n. [NL.] (Med.)
   Neuralgia of the sciatic nerve, an affection characterized by
   paroxysmal attacks of pain in the buttock, back of the thigh,
   or in the leg or foot, following the course of the branches
   of the sciatic nerve. The name is also popularly applied to
   various painful affections of the hip and the parts adjoining
   it. See Ischiadic passion, under Ischiadic.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Ischiadic \Is`chi*ad"ic\ ([i^]s`k[i^]*[a^]d"[i^]k), a. [L.
   ischiadicus, Gr. 'ischiadoko`s, fr. 'ischi`on the hip joint,
   hip or loin. Cf. Sciatic.] (Anat.)
   Ischial. [R.]
   [1913 Webster]

   Ischiadic passion or Ischiadic disease (Med.), a
      rheumatic or neuralgic affection of some part about the
      hip joint; -- called also sciatica.
      [1913 Webster]

WordNet (r) 3.0 (2006):

sciatica
    n 1: neuralgia along the sciatic nerve