1. a polyploid cell or organism.

Origin of polyploid

First recorded in 1915–20; poly- + -ploid
Related formspol·y·ploi·dic, adjectivepol·y·ploi·dy, noun
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for polyploidy


  1. (of cells, organisms, etc) having more than twice the basic (haploid) number of chromosomes
  1. an individual or cell of this type
Derived Formspolyploidal or polyploidic, adjectivepolyploidy, 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

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

polyploidy in Medicine


  1. Having extra sets of chromosomes.
  1. An organism with more than two sets of chromosomes.
Related formspoly•ploi′dy n.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

polyploidy in Science


  1. The state or condition of being polyploid.


  1. 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 © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.