The word "forum" has several related meanings, primarily centered around a place or medium for discussion and exchange of ideas. Historically, a forum was a large public space in ancient Roman cities used as a center for judicial and public business. More generally, it refers to a public meeting place or an event where people can openly discuss a particular subject.

In modern usage, a forum also means an online or offline platform where people can share opinions, debate, or exchange information about specific topics—such as internet forums where users post messages and engage in conversations that are often archived. Essentially, it is a public conversation or discussion space, physical or virtual, that allows people to communicate ideas and connect over shared interests.

Legally, a forum can also mean the jurisdiction or venue where a dispute is heard.

In summary, a forum is a place or medium for open discussion, whether a physical public space, a scheduled meeting, or an online discussion board.