Gratuituous could be used for free of charge since it's what we used in latin languages (which I suppose is the same root as gracious - at least in formal french we replace gratuit with gracieux to mean the same thing).

So I wonder if English, tired of borrowing a strange word, will use gracious or gratuitous some day to denote free of charge ! That would maybe avoid all these questions of what libre means !

I rarely use FLOSS as, floss is a known word for flossing teeth and for the dance move. Libre just sounds cool compared to floss.