A lot vs. Alot: 9 Grammatical Pitfalls
mid-15c., "place of assembly in ancient Rome," from Latin forum "marketplace, open space, public place," apparently akin to foris, foras "out of doors, outside," from PIE root *dhwer- (see door). Sense of "assembly, place for public discussion" first recorded 1680s.
(Plural "fora" or "forums") Any discussion group accessible through a dial-in BBS (e.g. GEnie, CI$), a mailing list, or a Usenet newsgroup (see network, the). A forum functions much like a bulletin board; users submit postings for all to read and discussion ensues.
Contrast real-time chat or point-to-point personal e-mail.