A power or right possessed by one department of government to
forbid or prohibit the carrying out of projects attempted by another
department; especially, in a constitutional government, a power vested
in the chief executive to prevent the enactment of measures passed by
the legislature. Such a power may be absolute, as in the case of the
Tribunes of the People in ancient Rome, or limited, as in the case of
the President of the United States. Called also the veto power.