It is a common notion that there is a lot of ambiguity and disagreement around the term Open Source. While that has been true in the past, I believe that there is much more consensus now because the term has been refined and the taxonomy of software has been improved. Certainly there are still arguments, but I believe for the most part, there is a detente.
Much of the past ambiguity surrounded the philosophical disagreements between those who felt software should be free as in liberty, not only free as in beer. This view essentially holds that derivative works of Free Software must themselves be open and Free. Richard Stallman (who does not want to be associated with the term Open Source) embodies this philosophy, as does the GPL license.
The opposition felt that we should not place such restrictions on software to consider it Open Source.
While this disagreement may have been heated at times, in many ways the core argument around the term Open Source has been resolved by differentiating between Free Software and Open Source. There are now sites dedicated to the Free Software Definition and the Open Source Definition to promote these terms.
While there are certainly disagreements between the two camps on how software should be licensed, in many ways the camps are compatible. When looking specifically at the licenses, it is helpful to think of Open Source as a superset of Free Software. Free Software is necessarily Open Source, but an Open Source is not necessarily Free Software because a Free Software license is in general as restrictive or more restrictive than an Open Source license.
Likewise a Source Available is not necessarily Open Source, but Open Source is necessarily Source Available.
In my hope to be a neologist, I will push the term Source Available (I like it better than my earlier term Code Available) and hope it catches on. If someone coined it before me, at least I hope the claim to fame of making it popular. ;)
I have written on the topic of Open Source software before if you are interested.