Uindemigender is an umbrella term for any demigender that is unknown, unnamed, undecided, unsure, undefined, unidentified, unquantifiable, unexplainable, or undetermined in nature (UIN). It is not the same as questioning, as an uindemigender person can be certain of the fact that their demigender is unidentifiable or unknowable. Uindemigender doesn't have to be a temporary state.
Uindemigender can also be used as a demigender on its own, referring to any demigender that is not fully unknown or undefinable. It is often used by people who are not able to narrow down their demigender any more than being unidentifiable.
History
The term uindemigender was coined by Tumblr user iceslushii on July 30, 2021, with both flags being made on the same day.