1Pathology and Biochemistry. The disintegration, dissolution, or disruption of cell nuclei; karyolysis. Also: the breakdown of nucleic acid molecules, especially by enzymatic activity.

2Surgery. The destruction of a nucleus in the central nervous system. rare.

3Surgery and Medicine. Destruction of the nucleus pulposus of an intervertebral disc, especially by the injection of an enzyme or chemical. Compare earlier chemonucleolysis.