• synonyms


[non-dis-juhngk-shuh n]
noun Biology.
  1. the failure of chromosomes to separate and segregate into daughter cells at division.
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Origin of nondisjunction

First recorded in 1910–15; non- + disjunction
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for non-disjunction

Historical Examples

  • Non-disjunction as proof of the chromosome theory of heredity.

    Sex-linked Inheritance in Drosophila

    Thomas Hunt Morgan

British Dictionary definitions for non-disjunction


  1. the failure of paired homologous chromosomes to move to opposite poles of the cell during meiosis
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Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for non-disjunction


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

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Online Etymology Dictionary, © 2010 Douglas Harper

non-disjunction in Medicine


  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.
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Related formsnon′dis•junction•al adj.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.