Uingender

Uingender is an umbrella term for any genders that are unknown, unnamed, undecided, unsure, undefined, unidentified, unquantifiable, unexplainable, or undetermined in nature (UIN).  It is not the same as questioning, as an uingender person can be certain in the fact that their gender is unidentifiable or unknowable. Uingender does not have to be a temporary state, and they do not have to be looking for to understand their gender.

It can also be used as a gender on its own, when being undefined is its main feature. It's often used by people who cannot narrow down their gender any more than being unidentifiable.

As for pronunciation, there is variation between the community. However, the most common pronunciations seem to be "oo-in-gender," "yoo-een-gender" and "yoo-in-gender."