Procedural step of ending debate on a proposal, and holding a vote to determine if it will pass. In the U.S. Senate, a three-fifths majority is usually required to invoke cloture, which translates to 60 votes if no vacant seasts exist. If debating a change to procedural rules, an even larger two-thirds majority is required in the Senate. In the U.S. House of Representatives, a simple majority suffices to cut off debate.
U.S. Senate Rule XXII