Cleft chin
A dimple or vertical groove in the middle of the chin.
Also: chin dimple, butt chin
A cleft chin has a small dimple or a Y-shaped line at its centre. It forms where the left and right halves of the lower jaw, or of the chin muscle above them, did not fully fuse before birth. It is often described as an inherited dominant trait, but its inheritance is not simple. Cleft chins are found among people everywhere. Film studios once prized them in leading men; today they are just one of many normal chins.