A "gender" where the adult party feels as if they are a kid trapped in an adults body. The adult party feels attraction to children as well...
"Hey man, I would like to come out to you as kindergender, I am a kid trapped and I want to love other kids"
"Isn't that PEDOPHILIA?"
"No, it's kindergender..."
While commonly defined as an LGBT term for pedophile, the term was actually concocted by 4chan's /pol/ board in order to make it seem like the LGBT/GSRM community harbors and encourages pedophilia, which is overwhelmingly not the case.
"Did you hear that LGBT people are trying to make pedophilia okay? They call it 'Kindergender'."
"No man, that was made up by 4chan. Being a pedophile doesn't make you LGBT, it just makes you in need of serious mental help."