What is the anatomical possession for "butt chin"?

What is the anatomical possession for "butt chin"?
As a healthcare provider I say: Give me a break. And for God's sake consent to go of this. It only just hurts people who hold this feature. The occupancy itself is derogatory. And there is no existing need for us to own a medical term for it. On the other paw we do have jargon for people who soak up this kind of humor.
It"s call a cleft
I think its call a cleft chin.