Weapon of mass destruction

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 (e.g., buildings), natural structures (e.g., mountains), 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 conventional explosives during World War II, it has later come to refer to large-scale weaponry of warfare-related technologies, primarily biological, chemical, radiological, or nuclear warfare. Protective measures against weapons of mass destruction are known as CBRN defense.