To Breed means to partake in the action of Breeding.
Breeding is the action of male and
female animals having
sex (or mating) to reproduce, and procreate.
Animals, including Humans breed with members of the opposite
sex within their own species due to a desire for sexual pleasure, love, and the need to propagate the next generation.
Without Breeding no Human being would be alive. Thus Breeding is essential to the existence of Humans and animals (unless they are a part of the small minority of species that reproduce asexually).
Heterosexual
sex is the only kind of
sex that can be described as Breeding.