One of the first things you notice when you start digging into the definitions of words is that they are much more ambiguous than they seem. Chairs are an excellent example as at first glance they don't seem ambiguous at all. But then, what if we ask if a tree stump is a chair if someone sits on it? This puzzle won't be a challenge for longtime readers of Less Wrong, as they should already understand that the map is not the territory. That is "chair" is a word created by humans and which exists for our purposes and for which we get to decide the convention. It's definition is not a fact written in the universe, waiting to be discovered.
I've started using the term Linguistic Freedom to refer to this use specifically, since just saying "The Map is Not the Territory" is somewhat ambiguous and also somewhat difficult to explain. On the first point, if you look at the post where Elizier describes the skill The Map Is Not the Territory, rather than talking about linguistic freedom, he talks about the potential of being wrong, epistemic humility and how beliefs are separate from reality. On the second, instead of just saying, "Words are created by humans for our purposes and so we get to decide if a treestump we sit on counts as a chair, it isn't written into the universe", while if we want to explain the "Map and Territory" we have to explain the map AND the territory AND then how it applies to language.
Anyway, all I mean by this is that we have the freedom to use language however we want, even if it is stupid. For example, we could use "chair" to mean "pineapples" and that would just be stupid rather than wrong. But what do we mean by stupid? One simple way of characterising this would be to note that the territory contains certain natural structures that cry out for a name and that a definition is "stupid" when the term was created in order to refer to some way of drawing boundaries around a particular natural structure, but we decide to ignore this.
Linguistic freedom is about conventions, not individual uses of language. It doesn't mean that I can start using "chair" to mean "pineapple" without telling anyone. It doesn't mean that if you ask "Do chairs typically have four legs?" that I can answer as though you asked about pineapples. I suppose we do have that kind of linguistic freedom to be stupid in that way as well, but that isn't the kind of freedom that I'm referring to. It also doesn't refer to any kind of subjectivism or anti-realism or notion that everything is just language games.
This sequence will argue that this principle applies far more widely than you might think; that is many unexpected things are actually part of the map.