A powerful strike delivered using the crown of the head, probably the strongest bone in the body, as the striking surface. When properly delivered the force comes mostly from the legs, with the entire body coordinated to deliver the blow. Usually delivered to the jaw or nose of an opponent, from below. A more clueless application of the technique may result in a skull to skull impact, a particularly stupid thing to do, which has given this move a bad name in many circles. However, delivered properly, it can inflict great damage with little loss.
A favourite maneuver of Muay Thai practitioners and Liverpool brawlers, among others.
Also known as a headbutt.