Informal options:
* Group: This is the most general and common term.
* Gathering: Implies a loose collection of people.
* Crowd: Usually used for a large, unstructured gathering.
* Assembly: More formal than "gathering," often used for a group that has come together for a common purpose, even if it isn't explicitly stated.
* Congregation: Typically used for a group of people gathered for religious purposes, but can also be used more broadly for any group that has come together for a shared purpose.
More specific options:
* Throng: For a large, dense crowd.
* Mob: Used for a large, unruly crowd, often with negative connotations.
* Herd: Used for a large, undifferentiated group, often with a humorous tone.
* Cluster: For a smaller, more localized group of people.
The best collective noun to use will depend on the specific situation and the tone you want to convey.