A multigender where someone who is part (a) xenogender (s) and part gendernull or both at the same time.
The nonbinary equivalent is Nullenby. The fluid equivalent is Xenullfluid.
History
The term Xenull was coined by tumblr user nonbiarrow on 09/05/2021, as well as its flag.
Flag
The flag shows three stripes: grey for gendernull, indigo for xenogender and light blue for being inbetween or both/all genders.