I think you're going to run into the same thing I ran into here https://news.ycombinator.com/item?id=20864837 which is that the term Open Source has been taken over by opensource.org.
Although I suppose you won't get as many downvotes as I did (the reason for which still eludes me)
> “which is that the term Open Source has been taken over by opensource.org“
https://opensource.org/history claims that the term did not really exist before those behind OSI/opensource.org started using it. While the originality of any composition of dictionary terms is debatable, I'm quite willing to accept that claim. I remember hot debates about the conceptual differences between FSF and OSI but none about prior use of the term.
Although I suppose you won't get as many downvotes as I did (the reason for which still eludes me)