A weapon of mass destruction (WMD) is a biological, chemical, radiological, nuclear, or any other weapon that can kill or significantly harm many people or cause great damage to artificial structures, natural structures, or the biosphere. The scope and usage of the term has evolved and been disputed, often signifying more politically than technically. Originally coined in reference to aerial bombing with chemical explosives during World War II, it has later come to refer to large-scale weaponry of warfare-related technologies, such as biological, chemical, radiological, or nuclear warfare.

A chemical weapon (CW) is a specialized munition that uses chemicals formulated to inflict death or harm on humans. According to the Organisation for the Prohibition of Chemical Weapons (OPCW), this can be any chemical compound intended as a weapon "or its precursor that can cause death, injury, temporary incapacitation or sensory irritation through its chemical action. Munitions or other delivery devices designed to deliver chemical weapons, whether filled or unfilled, are also considered weapons themselves."