Veto

The word 'veto' comes from a Latin word and literally means I forbid. It is used to denote that a certain party has the right to stop unilaterally a certain piece of legislation. In practice, the veto can be absolute (as in the U.N. Security Council, whose permanent members can block any resolution) or limited (as in the legislative process of the United States, where two-thirds of Congress can override the President's veto).

A veto gives power, possibly unlimited, to stop changes, but not to adopt them. The influence that the veto conveys to its holder is therefore directly proportional to the holder's conservatism, broadly defined. The more the holder likes the current state of affairs, the more useful the veto.

The veto originated with the Roman consuls and tribunes. Either of the two consuls holding office in a given year could block a military or civil decision by the other; any tribune had the power to unilaterally refuse legislation passed by the Roman Senate.citation needed]