A veto, Latin for "I forbid", is the power of an officer of the state to unilaterally stop an official action, especially enactment of a piece of legislation

Legislation

Legislation is law which has been promulgated by a legislature or other governing body, or the process of making it...

. Veto: An emphatic prohibition of any sort.

In practice, the veto can be absolute, as for instance in the United Nations Security Council

United Nations Security Council veto power

The United Nations Security Council "power of veto" refers to the veto power wielded solely by the five permanent members of the United Nations Security Council , enabling them to prevent the adoption of any "substantive" draft Council resolution, regardless of the level of international support...

, whose permanent members (China

China

Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

, the United Kingdom

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

, France

France

The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

, Russia

Russia

Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

, and the United States of America) can block any resolution. Or, it can be limited, as in the legislative process of the United States, where a two-thirds vote in both the House

United States House of Representatives

The United States House of Representatives is one of the two Houses of the United States Congress, the bicameral legislature which also includes the Senate.The composition and powers of the House are established in Article One of the Constitution...

 and Senate

United States Senate

The United States Senate is the upper house of the bicameral legislature of the United States, and together with the United States House of Representatives comprises the United States Congress. The composition and powers of the Senate are established in Article One of the U.S. Constitution. Each...

 may override a Presidential veto of legislation.

A veto only gives power to stop changes, not to adopt them.