A hole or a slot for receiving a key.

A welding method wherein the heat source, because of its concentration, causes a hole through the surface immediately ahead of the molten weld metal in the direction of welding; the hole is filled as the welding progresses, ensuring complete joint penetration.

Of a bullet, to strike a target after tumbling in flight so that the long axis of the bullet and the line of flight are not the same; usually caused by failure of the bullet to receive sufficient spin from the rifling in the barrel.