nullify
verb [ T ]
uk/ˈnʌlɪfaɪ/ us LAW
to make a legal agreement or decision no longer have any legal force:
The airline wants to nullify employees' contracts if no settlement is reached.
to cause something to have no value or effect:
A suit has been filed against the directors, charging them with conspiring to nullify a shareholder vote.
The US stated that any reductions in greenhouse gases by the West must not be nullified by increased emissions from developing nations.
nullification
noun [ U ]