Answer Win $0.55 - What is a forum?

Win $0.18 - What is a forum?
The last contest can be seen here.
If you haven't read the competition rules click here, and if you are a new member then read the forum rules here.

Because no one answered to the last contest, today we will add $0.18 to the question with the prize of $0.37. 0.18+0.37=0.55

Everyone is currently enrolling in a forum, but I have not seen anyone give a correct definition. So you have to answer two questions:
1. What is a forum?
2. Where does the word come from and what does it mean in that language?