heterozygous
1. having one or more sets of unlike alleles —note an Aa cell or plant is heterozygous whereas the AA and aa genotypes are homozygous 2. pertaining to differences in the arrangement of genes on chromosomes —note a heterozygous tree is called a heterozygote —see character, dominance, F1, F2, heterosis, hybrid, overdominanceThis definition last updated 12/09/2008