✦ multinonbinary can also be called multienban / multienby / polynonbinary / polyenban / polyenby / etc. ✦ multiabinary can also be called multiaban / multiaby / polyabinary / polyaban / polyaby / etc.
✦ multimidbinary can also be called multimban / multimby / polymidbinary / polymban / polymby / etc. ✦ multibinary can also be called multibian / multibinby / polybinary / polybian / polybinby / etc. ✦ multiatrinary can also be called multiatran / multiatry / polyatrinary / polyatran / polyatry / etc.
✦ multimidtrinary can also be called multimidtran / multimidty / polymidtrinary / polymidtran / polymidty / etc. ✦ multitrinary can also be called multitrian / multitriary / polytrinary / polytrian / polytriary / etc. ✦ multiandrogyne can also be called multiangan / multiangi / polyandrogyne / polyangan / polyangi / etc.
✦ multiagender can also be called multiagan / multiagie / polyagender / polyagan / polyagie / etc. ✦ multilyagender can also be called multilyaen / multienfil / polyilyagender / polyilyaen / polyenfil / etc. ✦ multiaporagender can also be called multiaporan / multiapory / polyaporagender / polyaporan / polyapory / etc.
✦ multioutherine can also be called multiouman / multioune / polyoutherine / polyouman / polyoune / etc. ✦ multikenochoric can also be called multiomen / multihex / polykenochoric / polyomen / polyhex / etc. ✦ multixenogender can also be called multixenan / multixip / polyxenogender / polyxenan / polyxip / etc.
ALT
I listed some examples, but other terms can be used too, as long as they have the same / similar meaning (e.g. multiaphorian instead of multiabinary).
Though I wrote them all as single terms, I suppose they can called multigender [term] and polygender [term] too (e.g. multigender enban instead of multienban). The short forms are just what I thought of first, but upon thinking about it more, I don’t see why the longer names wouldn’t work too.
You could also shorten them if you want (e.g. multixeno instead of multixenogender).
-✦
Also, I think these terms can include a lot of different experiences (any combination of multigender/polygender and the specific gender label listed), so I won’t be listing specific definitions.
ALT
For the flags, I followed a format of having multigender stripes on top (dark blue, lighter blue, and orange), with the respective gender’s stripes on the bottom. Specifically, I used this multigender flag edit (by @isobug) for the colours (same main colours as the original, just with nicer contrast).
Depending on the original flag, I combined the top colour with the bottom multigender orange stripe, if they’re similar enough visually (like the orange in nonbinary (second flag)). The multigender blue colours were edited a bit, to fit better with the other colours. And for some of them, I simplified the colours, they have as many stripes as in the original flag.
Special mention multitrinary and multiandrogyne, I went with a different style mimicking the original flags. Trinary used diagonal stripes, so I used diagonal stripes on the side here too. Same with androgyne, but with vertical stripes. For the trinary/androgyne colours that are already similar to the multigender colours (so blue and grey), I combined them into the 3 horizontal multigender stripes, and put the rest off to the side. It’s a lot like what I did in my butch/futch/femme/+ flags (not that these are butch/futch/femme flags). I just think it’s a unique format, and I like how it flows.