From Academic Kids
A supermajority or a qualified majority is a requirement for a proposal to gain a specified level or type of support which exceeds a simple majority in order to have effect. For example: in some jurisdictions, parliamentary procedure requires that any action that may alter the rights of the minority has a supermajority requirement (such as a two-thirds majority). Changes to constitutions, especially those with entrenched clauses, commonly require supermajority support in a legislature.
The United States Senate requires a supermajority of 60 percent to move to a vote through a cloture motion, which closes debate on a bill or nomination, thus ending a filibuster by a minority of members.
The United States Constitution requires a supermajority of two-thirds of both houses of Congress to propose a Congress-driven constitutional amendment; it also requires a three-fourths supermajority of state legislatures for final adoption of any constitutional amendment, as well as a two-thirds supermajority to pass a bill over the president's veto.