Do you know the difference between 'meeting' and 'reunion'? And what about 'gathering'?
A meeting is any kind of gathering of people, a reunion is a meeting where people get back together. For example a school reunion, where former students meet up again after they have left school.
A meeting is an assembly of people, either by chance or by prior arrangement. This is the most generic term that covers the coming together of two or more people. A gathering is a meeting or an assembly held especially for a social or festive purpose (e.g. a family gathering).
And here's a most completed explanation provided by BBC Learning English.