Two or more presences held in one place and time by arrangement rather than accident. The gathering that must be agreed to before it can happen.
Old English gemēting (an assembly, encounter), from mētan (to meet, find, encounter), from Proto-Germanic *mōtjaną, from *mōtą (a meeting, assembly) — the same root as MOOT, the Anglo-Saxon assembly where matters were decided. Cognate with Old Norse mót. The oldest sense is the COMING TOGETHER itself, not the room or the agenda.
The realm for recording what was actually said when people came together. The moot sense is the useful one: a meeting is an assembly with consequence, and the point of keeping it is that decisions made in a room evaporate unless someone writes them down.