Unmature 

It means the same thing as immature, just this way of saying/spelling it is so much better. Hey, it makes sense doesn't it? Yes. It definitely does.

Stop being so unmature.

Unmature by Ashley Aguiar December 10, 2004

Unmature 

When Graeme Carry's on and thinks he's funny

Graeme your so unmature when u talk shit and tell your dumb dad jokes

Unmature by Not mature January 28, 2019

Unmature 

Unmature: Consistently insulting someone daily for no good reason. And getting mad at someone for nothing.

I made this up

You are Unmature dude

Unmature by Tommish August 1, 2021