non-disjunction

noun Biology.

1. the failure of chromosomes to separate and segregate into daughter cells at division.

noun

1. the failure of paired homologous chromosomes to move to opposite poles of the cell during meiosis

n.also nondisjunction, 1913, from non- + disjunction. Related: Non-disjunctional. n.

1. The failure of one or more pairs of chromosomes to separate at the miotic stage of karyokinesis, with the result that both chromosomes are carried to one daughter cell and none to the other.