Public medium (such as a newspaper column) or place used for debates in which anyone can participate. In Roman times it meant a public place at the center of a market or town where open discussions on judicial, political, and other issues were held. Read more
USAGE EXAMPLE
Twitter is a public forum, on which people of all backgrounds with all sorts of interests may post their opinions, comments, et cetera and then receive nearly immediate feedback from those who see their tweet in their timeline.