Other forms: symposia; symposiums
A symposium is a public meeting about a topic in which people give presentations. If your knitting club holds a symposium, various knitters will give presentations about anything having to do with knitting.
A symposium can be a one-time conference or a regular meeting, but it will probably include some amount of discussion or public speeches on a particular subject. Many people who attend symposiums will be part of the audience for many of the presentations, but during the course of the event, give their own presentation or be part of a panel discussion.