Open source means you can read the source, much like an “open book exam” means you can read the book. The correct term for software that belongs to the community is Free Software. With Free Software, you are guarenteed to have the four fundamental software freedoms. With “Open Source”, there is no such guarentee.
By my definition, even Windows is Open Source. In principle, I can view the source code to Windows. It’s difficult and I have to sign a whole bunch of documents but I could do it with sufficient patience. This is why I don’t like Open Source as a term; it is far too misleading. In fact, it doesn’t actually mean anything other than the fact there is a mechanism by which you can see the source code that doesn’t involve getting a court-order.
In contrast, the term Free Software has a very precise meaning and really should be trade-marked by the FSF. Then the FSF could only issue licenses to se the trade-mark where the software is licensed that protects the four freedoms. This way, companies couldn’t profit from the name unless they labelled their products correctly.