Definition: an unifying term for non-binary people whose gender-ness is at least: 

changing in intensity &/or identity (flux/fluid);

multiple/plural (multigender/plurigender);

divided/separated in parts (demigender);

mixed/combined (genderpotion/shuffler);

(in)between genders (centrigender);

reference gender binary (midbinary);

lia-/fia-/mia-gender (wif-/wer-gender);

other adjacent/aligned/similar experiences.

Po- is a play on apo-/apora- (which means separation), without a- it’s not essentially like that, while -oxo from roxo, meaning purple (do not confuse with proxogender and purplegender). The concept comes from the non-binary flag purple meaning:

Purple represents the fluidity and multiplicity of many gender experiences, the uniqueness and flexibility of nonbinary people, as well as representing those whose gender experiences include being of or between female and male.

Genderfluidity is synonymous to genderflexibility and genderflux to flexgender, but for in case of uniqueness, I imagine that some people that have their gender split/merged/partly (dis)identified while still monogender (being only one/singular gender), almost like gendervast.

“...being of or...female and male” gives some ambiguity if it’s both (femache) &/or one of them. And since it’s not mentioned ideogenders/bingenders (lin-/fin-/min-gender), I’m not putting them there inherently. Gender partialities/partial genders are included as demigenders.