quorum

The minimal number of officers and members of a committee or organization, usually a majority, who must be present for valid transaction of business.

A select group.

The minimal density of bacterial cells that results in altered gene expression in a population of bacteria.

In England, those justices of the peace whose presence is necessary to constitute a bench.

The number of members of any constituted body of persons whose presence at or participation in a meeting is required to render its proceedings valid, or to enable it to transact business legally.

Requisite materials.

Such a number of the officers or members of any body as is competent by law or constitution to transact business

The minimum number of members required for a group to officially conduct business and to cast votes, often but not necessarily a majority or supermajority.

A selected body of persons.

a gathering of the minimal number of members of an organization to conduct business