Sciatica:

A condition characterized by pain radiating from the back into the buttock and posterior/lateral aspects of the leg. Sciatica may be a manifestation of SCIATIC NEUROPATHY; RADICULOPATHY (involving the L4, L5, S1 or S2 SPINAL NERVE ROOTS; often associated with INTERVERTEBRAL DISK DISPLACEMENT); or lesions of the CAUDA EQUINA.