What term describes an unorganized group that comes together for a meeting?

The correct term for an unorganized group that comes together for a meeting is "mass meeting." A mass meeting is typically characterized by its informal nature, where individuals gather to discuss common interests or to address a particular issue without requiring any formal structure or predefined agenda. This format is often used when there is a need for community engagement or to mobilize people quickly around a specific topic or cause.

In the context of meetings, it contrasts with formal assemblies, which have a structured agenda and specific rules governing the proceedings. A "special session" refers to a meeting convened for a specific, often urgent purpose, usually within an established organization or legislative body, implying some level of organization. "Order of business" pertains to the agenda or procedural rules that guide how a formal meeting is conducted, focusing on the sequence of items to be discussed rather than the gathering of attendees. Thus, the term "mass meeting" aptly captures the essence of an unorganized group coming together without the constraints of formality.