A deadly weapon, sometimes dangerous weapon (although some jurisdictions differentiate between the two) or lethal weapon, is an item that can inflict mortal or great bodily harm. By statutory definition, certain items, especially firearms, are designated "deadly weapons per se", meaning they are regarded as deadly weapons no matter how they are used, from the Latin for "by itself".[1] In addition, deadly weapons statutes often contain provisions covering other implements intended to be used to inflict harm.
The use or possession of a deadly weapon during the commission of a crime often constitutes a penalty enhancer. The deadly weapon penalty enhancer is premised on a belief that commission of the particular crime is inherently more dangerous.
In some jurisdictions, a distinction is made between deadly weapons and destructive devices, such as explosives, incendiary or poison gas, bombs, grenades, landmines, rockets, missiles, or similar devices, including the unassembled components from which such devices can be made.