Herniation of the membranes of the brain or spinal cord (see meninx) through a defect in the cranium or spinal column.
Source:
PAC, 2016, 88, 713. 'Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)' on page 777 (https://doi.org/10.1515/pac-2015-1202)