The number of sets of chromosomes in a cell, or in the cells of an organism.
- ‘Grass genomes differ greatly in chromosome number, ploidy level, and size.’
- ‘Four of the chromosome counts represented new ploidy levels.’
- ‘Chromosome number and ploidy vary greatly and there is much overlap between them.’
- ‘We used pollen grain size as an indicator of ploidy level by measuring length and width of the pollen grains under a microscope.’
- ‘Leaf size is increased by greater cell ploidy, but the mechanism of this effect is poorly understood.’
1940s: from words such as (di)ploidy and (poly)ploidy.