• synonyms


[ kroh-muh-sohm ]
/ ˈkroʊ məˌsoʊm /

noun Genetics.

any of several threadlike bodies, consisting of chromatin, that carry the genes in a linear order: the human species has 23 pairs, designated 1 to 22 in order of decreasing size and X and Y for the female and male sex chromosomes respectively.

Nearby words

Origin of chromosome

First recorded in 1885–90; chromo- + -some3
Related forms Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for nonchromosomal


/ (ˈkrəʊməˌsəʊm) /


any of the microscopic rod-shaped structures that appear in a cell nucleus during cell division, consisting of nucleoprotein arranged into units (genes) that are responsible for the transmission of hereditary characteristicsSee also homologous chromosomes
Derived Formschromosomal, adjectivechromosomally, adverb
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 nonchromosomal



1889, from German Chromosom, coined 1888 by German anatomist Wilhelm von Waldeyer-Hartz (1836-1921), from Latinized form of Greek khroma "color" (see chroma) + -some (3)). So called because the structures contain a substance that stains readily with basic dyes.

Online Etymology Dictionary, © 2010 Douglas Harper

Medicine definitions for nonchromosomal (1 of 2)


[ nŏn′krō-mə-sōməl ]


Not situated on or involving a chromosome.

Medicine definitions for nonchromosomal (2 of 2)


[ krōmə-sōm′ ]


A threadlike linear strand of DNA and associated proteins in the nucleus of animal and plant cells that carries the genes and functions in the transmission of hereditary information.
A circular strand of DNA in bacteria and cyanobacteria that contains the hereditary information necessary for cell life.
Related formschro′mo•somal (-sōməl) null adj.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Science definitions for nonchromosomal


[ krōmə-sōm′ ]

A structure in all living cells that consists of a single molecule of DNA bonded to various proteins and that carries the genes determining heredity. In all eukaryotic cells, the chromosomes occur as threadlike strands in the nucleus. During cell reproduction, these strands coil up and condense into much thicker structures that are easily viewed under a microscope. Chromosomes occur in pairs in all of the cells of eukaryotes except the reproductive cells, which have one of each chromosome, and some red blood cells (such as those of mammals) that expel their nuclei. In bacterial cells and other prokaryotes, which have no nucleus, the chromosome is a circular strand of DNA located in the cytoplasm.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.