Homozygote The term coined by Bateson and Saunders (1902) for a zygote, or a diploid individual derived from it, which carries only one member of the alleles of a gene, that is, a zygote derived from the union of gametes identical (Gk. homos, alike) in respect of a particular gene. The same allele is present at a given locus. Cf. homozygosity