The minimum number of members of an assembly or committee that must be present for proceedings to be valid and decisions to be binding.

From the Latin quorum, meaning of whom — taken from the wording of writs issued to justices of the peace, requiring that certain named individuals be among those present.

In Quaker religious meetings, quorum has a specific theological meaning — the gathered community reaches quorum not through numbers alone, but through a sense of spiritual unity.

The concept has been extended to biology, where quorum sensing describes how bacteria communicate and coordinate behaviour once their population reaches a threshold density.

The phrase in quorum, used by the Roman Senate to indicate a valid session, is the origin of both the English quorum and the French phrase en corps, meaning as a collective body.