In biology a hybrid, also known as cross breed, is the result of mixing, through sexual reproduction, two animals or plants of different breeds, varieties, species or genera. Using genetic terminology, it may be defined as follows.

1. Hybrid generally refers to any offspring resulting from the breeding of two genetically distinct individuals, which usually will result in a high degree of heterozygosity, though hybrid and heterozygous are not, strictly speaking, synonymous.
2. a genetic hybrid carries two different alleles of the same gene
3. a structural hybrid results from the fusion of gametes that have differing structure in at least one chromosome, as a result of structural abnormalities
4. a numerical hybrid results from the fusion of gametes having different haploid numbers of chromosomes
5. a permanent hybrid is a situation where only the heterozygous genotype occurs, because all homozygous combinations are lethal.