I will also point out that the correct term is GNU/Linux and that Open Source is different from Free Software (though both may be collectively called a term which is gaining acceptance in South Asia too -- Free/Libre and Open Source Software). FN
The nice thing about "free software" is that free-as-in-freedom can be easily and unambiguously translated into local languages. The same cannot be said about "open source" -- compare "swatantra software" with "khula source" (Hindi), for instance, and judge which one makes more sense. (Adding the word "Libre" too doesn't help much in a regional context because it simply addresses a couple of European languages.)
That's a practical and non-ideological reason for choosing the term "free software" with the word "free" replaced by "swatantra" or its regional equivalent. Of course, when you add ideology to the picture, the choice becomes even easier :)
"Swatantra software" is far more people friendly compared to FLOSS which just sounds like computer (or dental :) jargon.