Hemigender is a subset of demigender in which one's gender is exactly half a given gender and half something else. Hemigender can be combined with the relevant gender (hemiboy, hemigirl, heminonbinary, etc.) For example, a hemiboy would be exactly 50% boy, with the remaining 50% being something else. The other half can be any gender or combination of genders, including agender.
Heminonbinary (2) by Pride-Flags on DeviantArt
Hemigirl (1) by Pride-Flags on DeviantArt
Hemiboy (2) by Pride-Flags on DeviantArt