Terminology

Various terms used to talk about the same thing :

Free Software
OpenSource Software (OSS)
Libre Software / Software Libre
... and of course various languages (Software Libero (italian), Software Livre (portuguese), Freie Software (german), Logiciel Libre (french), etc.)

Debate on terminology... Free Software vs. OpenSource (more on this later)

More recently, some new terms appeared : F.L.O.S.S. : Free/Libre/OpenSource Software, for instance in some EC reports/papers.