Noun
1. The destructive fragmentation of the nucleus of a dying cell whereby its chromatin is distributed irregularly throughout the cytoplasm. It is usually preceded by pyknosis and is followed by karyolysis and can occur as a result of either programmed cell death or necrosis. (wikipedia.org)
2. Fragmentation of the nucleus whereby its chromatin is distributed irregularly throughout the cytoplasm; a stage of necrosis usually followed by karyolysis. (medilexicon.com)
3. Degeneration of the nucleus of a cell. There is contraction of the chromatin into small pieces, with obliteration of the nuclear boundary. (biology-online.org)
Word origin: From Greek karyon “nut, kernel” + rhexis, “rupture.”