What is veto?
Presidential disapproval of a bill or joint resolution presented to him for enactment into law. If a president vetoes a bill, it can become law only if the House and Senate separately vote (by two-thirds) to override the veto. A less common form of presidential veto – a pocket veto – occurs if Congress has adjourned without the possibility of returning and the president does not sign the measure within the required 10-day (excluding Sundays) period.
reference: Congress GlossaryWhat is