According to the Constitution, a quorum is a majority of those holding office; thus for the Senate it is fifty-one Senators. Generally it is assumed there is a quorum present unless there is a quorum call, i.e. a request to establish that there really is a quorum.

It is called a Quorum.

the short quorum crumbled the house in two hours.

As part of the Quorum Presidency, he will share duties concerning the welfare of the members of his Quorum and the duties of the Quorum. In the absence of the Quorum president, he will take the president's responsibilities.

A quorum is usually a majority of the members