deadly weapon

Definition from Nolo’s Plain-English Law Dictionary

A gun or other instrument, substance, or device, which is used or intended to be used in a way that is likely to cause death. A prosecutor who charges a defendant with "assault with a deadly weapon" must prove not only that the defendant assaulted the victim, but did so with a device that was capable of causing death. Some laws list "deadly weapons per se," which are weapons that by themselves are likely to cause death, such as a gun, regardless of the user's intent.

Definition provided by Nolo’s Plain-English Law Dictionary.