[ghaff]

The SQLite distinction is because it's public domain which the OSI doesn't consider open source mostly because "public domain" can have a somewhat funny legal status. https://opensource.org/node/878

So, yes, you can have an open source license that isn't OSI approved. However, leaving aside a few edge cases like public domain, there's pretty wide acceptance of OSI licenses as the population of significant open source licenses.

[ADDED:In practice, the FSF's list of free software licenses and the OSI approved license list line up pretty closely--with the exception of PD+source. If someone wants to argue that the FSF's list is the one we should go by, I'm not really going to argue.]

I do think it is potentially appropriate to have thoughtful discussion over whether the current open source definition is too narrow but I also think it is useful to have a generally agreed-on definition.