(In mitosis) The failure of sister chromatids to separate during and after mitosis.
(In meiosis) The failure of homologous chromosomes to segregate or to separate during and after meiosis.
This could result to a condition wherein the daughter cells have an abnormal number of chromosomes; one cell having too many chromosomes while other cell having none.
Examples of nondisjunction:
Related forms: nondisjunctional (adjective).
Related terms: meiotic nondisjunction.
See also: anaphase.