the forbidding or banning of something by somebody in authority

the right to forbid or ban something, e.g. a proposal

a right formally vested in a person or constitutional body to declare decisions made by others to be inoperative, esp a power vested in a chief executive, e.g. the president of the USA, to prevent permanently or temporarily the enactment of measures passed by a law-making body, e.g. Congress

the exercise of such authority

a message communicating the reasons for vetoing a proposed law