Xenogeneic refers to something that is derived from a different species. There are several synonyms for this term such as heterologous, allogenic, and cross-species. Heterologous is often used in reference to immune responses, while allogenic is commonly used in transplantation medicine. Cross-species is another way to describe something that comes from a different animal species. In the realm of genetics, the term xenogeneic is often used to refer to gene transfer between different species. All of these words convey the idea of something being foreign or unfamiliar, and highlight the importance of understanding the source and implications of these types of materials.