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[pol-ee-ploid] /ˈpɒl iˌplɔɪd/ Biology
having a chromosome number that is more than double the basic or haploid number.
a polyploid cell or organism.
Origin of polyploid
1915-20; poly- + -ploid
Related forms
polyploidic, adjective
polyploidy, noun Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for polyploidy
  • Instead of making gametes with only one copy of each chromosome, they created ones with two or more, a state called polyploidy.
  • What is really cool about polyploidy in plants is the immediate divergence to a new species that often accompanies it.
  • Of course, there's also the favorite of plants: polyploidy.
British Dictionary definitions for polyploidy


(of cells, organisms, etc) having more than twice the basic (haploid) number of chromosomes
an individual or cell of this type
Derived Forms
polyploidal, polyploidic, adjective
polyploidy, noun
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
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Word Origin and History for polyploidy

1922, from German polyploidie (1910), from polyploid, from Greek poly- (see poly-) + -ploid, from comb. form of ploos "fold" (see fold (v.)) + -oid.

Online Etymology Dictionary, © 2010 Douglas Harper
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polyploidy in Medicine

polyploid pol·y·ploid (pŏl'ē-ploid')
Having extra sets of chromosomes. n.
An organism with more than two sets of chromosomes.

pol'y·ploi'dy n.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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polyploidy in Science
The state or condition of being polyploid.
Having more than two complete sets of chromosomes. Many plants that are polyploid, such as dandelions, are sterile but can reproduce by apomixis or other asexual means. Other polyploid plants are fertile. For example, durum wheat (Triticum turgidum durum), which is used to make pasta, is tetraploid (it has four sets of chromosomes), while bread wheat (Triticum aestivum) is hexaploid (six sets of chromosomes). Polyploid plants, if viable, are often larger or more productive than diploid plants, and plant breeders often deliberately produce such plants by crossing species or other means. In the animal kingdom, polyploidy is abnormal and often fatal.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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