Abditivusfluid is a fancy way of saying genderfluid/polygender defined as "a fluid gender that separates itself from other genders, only taking a few with it to be fluid between."
Abditivusfluid was coined on December 15, 2019 by tumblr user hawaiiaine (aka gendernovus, genderstalgia, genderpotion, exosphenic, genderrose, mason-the-owlkin, atergender, beysgender, mogai-minecraft-snail, polysexualtea, aresgoesgender, thepancherryblossom). The flag was created at the same time.