(n) a not uncommon congenital defect in which a vertebra is malformed; unless several vertebrae are affected or there is myelomeningocele there are few symptoms; can be diagnosed by amniocentesis, Syn. rachischisis, schistorrhachis
The Collaborative International Dictionary of English (GCIDE) v.0.53 Collaborative International Dictionary (GCIDE)
‖ (Med.) [ L., cleft spine. ] A congenital malformation in which the spinal column is cleft at its lower portion, and the membranes of the spinal cord project as an elastic swelling from the gap thus formed. [ 1913 Webster ]