A loitering munition is a drone that circles over an area until it finds a target, then dives into the target and explodes. It is also called a suicide drone or a kamikaze drone. The word loiter means to wait in one area. The drone carries an explosive as its payload, so it is used once. Depending on its size, it is launched from a tube, from a rail or by hand.
It differs from a missile in one way. A missile is fired at a target that is already chosen. A loitering munition is launched first and chooses later. It also differs from an armed drone. An armed drone fires a weapon and then flies back to be used again. A loitering munition is itself the weapon.
Consider a valley where a hostile radar is moved between hiding places and is switched on for only a few minutes at a time. By the time a missile reaches the radar's last known position, the radar has moved. A loitering munition is sent into the valley first and waits there. When the radar switches on and the camera shows the vehicle that carries it, the operator can send the drone at it within seconds.
The target is found by computer vision for drones. This is an AI model that recognises what the camera sees, such as a vehicle or a radar. In some designs, the operator confirms the target before the dive. In others, the drone decides alone. This difference is the level of autonomy. How much a machine should decide alone in war is being argued while such systems are built.
A loitering munition is a special kind of drone. It is flown and watched from a ground control station.