the act of reducing or giving up weapons.

Originally a cold war term used to describe ongoing negotiations between the superpowers to limit and eventually dismantle weapons systems; now describes the diplomatic work of convincing nations to stop or reverse the production of weapons (especially nuclear).

the policy of eliminating a state’s offensive weaponry; may occur for all classes of weapons or for specified weapons only; the logic of the policy is that fewer weapons leads to greater security (156)

The reduction, limitation or complete abandonment of a nation's armed forces and military equipment (nuclear disarmament - abandonment of nuclear weapons).

Disarmament means the act of reducing or depriving arms i.e. weaponry.