Hollow-point bullet
A hollow point bullet is a bullet that is designed to expand upon entering a target. Unlike a full metal jacket bullet, the jacket metal does not cover the entire bullet and an area near the nose is left uncovered. A pit is then drilled into the front of the nose. When the bullet strikes a soft target, the pressure in the pit forces the ring of lead around it to expand greatly into a mushroom-shape. This causes considerably more soft-tissue damage than had the nose stayed intact.
The Geneva Conventions prohibit the use of expanding or fragmenting bullets in warfare, but the hollow point bullets are widely used for pistol ammunition.
The hollow point bullet is also referred to as the 'dum dum', and is similar to the cross point which uses two slits instead of a pit.