FLOSS & FOSS

To emphasize that “free software” refers to freedom and not to price, we sometimes write or say “free (libre) software,” adding the French or Spanish word that means free in the sense of freedom. In some contexts, it works to use just “libre software.”

From www.gnu.org/philosophy/floss-and-foss.en.html

They also say:

We in the free software movement don’t use either of these terms, because we don’t want to be neutral on the political question. We stand for freedom, and we show it every time—by saying “free” and “libre”—or “free (libre).”