Cross-breeding is a process that involves breeding two different organisms of the same species. However, in the world of biology, there are a few antonyms for the term "cross-breeding." One of them is "inbreeding," which is the act of breeding closely related individuals within a species. This process can lead to a higher probability of genetic diseases and disorders. Another antonym for cross-breeding is "purebreeding" or "inbreed line breeding," which involves the mating of animals within the same breed to maintain certain desirable genetic traits. While inbreeding and purebreeding could be advantageous in certain contexts, they can also lead to genetic health problems, making cross-breeding the preferred method for developing new and healthier species.