Billiogender is a multigender, that is a subset of mathgender, in which one feels as though they have, experience, or encompass a billion genders. It is similar to centilliogender, milliogender, kilogender, platilligender, trilligender, and zilliogender. It may also be considered a subset to pangender.
History
Billiogender was coined on July 31, 2018 by tumblr user arco-plurish.
Flag
There are 9 individual sections on the flag to represent the supposed 9 zeroes in the number billion, and the pi symbol represents the seemingly unending complexity and vastness of billiogender.