Any reader of this site will notice that we often talk about 'Free and Open Source Software' which we usually abbreviate as FOSS. For those who aren't intimately familiar with the history, trajectory, and nuances (warning - they are big topics) of the Free Software and Open Source Software camps - both subsets of information technology, itself a subset of digital technology - its significance is both arcane and something of a barrier to understanding.
Free Software has always had the very unfortunate ambiguity in the English-speaking world due to the word "Free" having two major meanings: free as in liberty or freedom or speech, or free as in gratis or no-cost. It seems that for most, they focus on the latter meaning and miss the point of the name. It's a constant battle to explain it to people ('free as in freedom, not free as in beer" is what you'll often hear). But, as any marketer will tell you, if you have to explain it, it's a failed band.
To be clear, even though most 'Free Software' is available at no cost, that is coincidental. The word Free in this case does not refer to cost, but rather the freedoms available to the users of the software. It is quite possible for 'Free Software' to be both 'commercial', and available at a cost, taking into account that any user has the freedom to distribute the source code at any price they want, including gratis.
The term "open source" is better marketing, in that it describes some relatively unambiguous properties of software - that the source code is available for others to view and, usually, do other things with, with various strings attached, depending on the perspective of the onlooker - but it fails to connote any of the philosophical values held by those who engage in creating, maintaining, and using it. It describes a few properties of a software project, but it doesn't offer insight into why that software is open source, which many of us think is crucially important.
In light of these short comings of both Free and Open Source Software as terms to describe what is important to us at the OER Foundation, we have started referring to 'LibreSoftware' instead. Even though, in the Angelosphere, schools are rapidly (but foolishly, in my opinion) decommissioning their Latin departments, most English-speakers have a passing familiarity with the world 'libre' - the root of liberty. It doesn't have the ambiguities of 'free', and it succinctly puts the affordances of 'Free Software' front-and-centre. It also brings us English-speakers in line with many other cultures with romance languages, where libre is well understood. So that's why we've started talking about LibreSoftware instead of FOSS.