Vetoing refers to the power held by the president (or other executive authorities) to reject or refuse approval of legislation passed by Congress before it becomes law. By vetoing a bill, the president can prevent it from being enacted unless overridden by Congress with enough votes.
Related terms
Override: This term refers to Congress' ability (with sufficient votes) to pass a bill into law even if the president has vetoed it.
Pocket Veto: A pocket veto occurs when the president takes no action on a bill during the final 10 days of a congressional session, effectively preventing its passage.
Line-item Veto: Line-item veto allows the executive to reject specific sections or provisions of a bill without rejecting the entire piece of legislation. However, this power is not held by the U.S. president.