Definition of diploid in US English:



  • 1(of a cell or nucleus) containing two complete sets of chromosomes, one from each parent.

    Compare with haploid
    • ‘We performed a similar experiment using h/h diploid cells as the host.’
    • ‘We started the experiments described below by establishing large populations of diploid cells.’
    • ‘Oocytes and sperm are haploid, with one set of chromosomes, whereas somatic cells are diploid, with two chromosomal sets.’
    • ‘However, to a low extent, viable spores can also be recovered from a very small population of homozygous diploid nuclei in an otherwise haploid plasmodium.’
    • ‘An obvious question is whether the mat bias is absent in azygotic meiosis after homologous chromosomes have coexisted in diploid cells for many mitotic divisions.’
    1. 1.1 (of an organism or part) composed of diploid cells.
      • ‘We examined the genetics of hybrid incompatibility between two closely related diploid hermaphroditic plant species.’
      • ‘Note that copy numbers in tetraploids were slightly less than double those in respective diploid progenitors.’
      • ‘Currently, six major tetraploid races are recognized and their diploid progenitors have been identified.’
      • ‘The practical application that is considered is the full-sib family of a diploid outbreeding species.’
      • ‘The compactness of rice and sorghum genomes is evident compared to barley and diploid wheat genomes.’


  • A diploid cell, organism, or species.

    • ‘In diploids, sexual reproduction promotes both the segregation of alleles at the same locus and the recombination of alleles at different loci.’
    • ‘The diploid ancestor could not be identified because among the South American diploids there were no species matching in the FISH or RFLP pattern of rDNA.’
    • ‘Previous work has calculated the covariance expected under autosomal inheritance in diploids and haploids.’
    • ‘Arabidopsis thaliana and many closely related species are diploids with relatively few recent gene duplications.’
    • ‘We conclude that the haploids had a greater frequency of mutant phenotypes than the diploids.’


Late 19th century: from Greek diplous ‘double’ + -oid.