It's not popular, but even creative commons, the organisation that wrote the licence they are using, prefers the term "free cultural work" https://creativecommons.org/public-domain/freeworks/

They're "we won't sue you for using these" bytes. The terminology might be fuzzy but I feel like everyone in this thread understands the concept.

But... you'll see Netflix calls it "OPEN SOURCE CONTENT" if you click the link.

I believe open source is about the law. Software is one way it can be applied.