in brief, a xenogender is a nonbinary identity that references concepts, animals, plants, or objects in reference to one’s gender expression. this does not mean that someone identifying with a cat xenogender believes that their gender is a cat, for example; rather, their associations with cats align with their associations of their own gender.
xenogenders were created by neurodivergent individuals (austistic, adhd, etc) as a way to express their gender identities in a way that feels authentic and reflects the impact their neurodivergence has on their gender.
neurotypicals (those without autism, adhd, etc) are usually permitted and encouraged to use xenogenders if they want to, although some xenogenders are very closely intertwined with meurodivergent experiences.