According to Merriam-Webster:

Main Entry: fo·rum Pronunciation: 'fOr-&m, 'for- Function: noun Inflected Form(s): plural forums also fo·ra /-&/ Etymology: Latin; akin to Latin foris outside, fores door -- more at DOOR 1 a : the marketplace or public place of an ancient Roman city forming the center of judicial and public business b : a public meeting place for open discussion c : a medium (as a newspaper) of open discussion or expression of ideas 2 : a judicial body or assembly : COURT 3 a : a public meeting or lecture involving audience discussion b : a program (as on radio or television) involving discussion of a problem usually by several authorities