You mean like mesotrois/centrois or centrigender? It's like being the zero in the Cartesian system, centered in the middle of the spectrum.

Some people interpret their gender as in-between two genders in a linear spectrum. Specially when it's interchangeable with neutral gender/neutrois.

Mesotrois:

neutral leptrois, leptive neutrois; 

the middle of ambitrois & nulltrois poles;

middle of positrois & negatrois extremes;

intermediating pillars/limits of leptivity;

leptral equivalent of zero quantity;

equigender or equilibriogender;

gender equilibrium/balance;

gender equary/equiry;

nongender(s).

Term suggested by @neutrois-maverique-blog since neutrois-ness was so easy to misrepresent and misapply the leptive system in some ways. Anyway it’s just to specify a gender that is in the middle of leptivities.