The terms cleft chin, chin cleft, butt chin, superhero chin, dimple chin, or a chin dimple refer to a dimple

Dimple

A dimple is a small natural indentation in the flesh on a part of the human body, most notably in the cheek or on the chin.-More about dimples:...

 on the chin

Chin

In the human anatomy, the chin is the lowermost part of the face.It is formed by the lower front of the mandible.People show a wide variety of chin structures. See Cleft chin....

. It is a Y-shaped fissure on the chin with an underlying bony peculiarity. The chin fissure follows the fissure in the lower jaw

Jaw

The jaw is any opposable articulated structure at the entrance of the mouth, typically used for grasping and manipulating food. The term jaws is also broadly applied to the whole of the structures constituting the vault of the mouth and serving to open and close it and is part of the body plan of...

 bone resulted from the incomplete fusion of the left and right halves of the jaw bone, or muscle, during the embryonal and fetal development.