A forward dislocation of one vertebra over the one beneath it producing pressure on spinal nerves

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
medical Latin, from Greek spondylos (see spondylo- ) + oliothesis "dislocation, slipping."

Wikipedia Word definitions in Wikipedia
Spondylolisthesis is the forward displacement of a vertebral bone in relation to the natural curve of the spine, most commonly occurring after a fracture, and most often the fifth lumbar vertebra . Backward displacement is referred to as retrolisthesis ...

WordNet Word definitions in WordNet
n. a forward dislocation of one vertebra over the one beneath it producing pressure on spinal nerves

Wiktionary Word definitions in Wiktionary
n. (context medicine English) A forward displacement of a vertebra over a lower vertebra, due to a congenital defect or injury