Worth noting that "open-source" doesn't imply a license to use the software in any way. You can put up a project on Github with "all rights reserved" (though you obviously grant Github rights to distribute it when you upload it).
I chose the most literal definition because it's complicated. Debian calls it "free software," but that has its own issues because there's "freeware" where source might not be available and the license isn't permissive. Then there's the JSMin "no evil" (unless you're IBM, its customers, partners, or minions) license.
> I chose the most literal definition because it's complicated.
That's not the most literal definition, and it's not complicated once you know what it is. Open source[1] is a term coined by people decades ago to refer to something very specific, not "source code can be seen". There are specific licenses that are considered open source, and others that are not. Open source specifically requires a license that allows certain capabilities.
You can read more about this at https://opensource.org/. There's been some misunderstanding over the years where people (including me) have misapplied the term to mean you can access the source, but that's not really what it means, so we shouldn't dilute its meaning by allowing that.
> Debian calls it "free software,"
Free software is also a term used to refer to open source.[2]
I understand it can feel pedantic to have this terminology so strongly enforced, but the reason people do so is because there have been efforts by commercial entities to co-opt the term for their own version of software and software as a service which does not conform to what open source stands for, and ride on the coattails of the movement and good disposition towards open source. Your first comment actually seemed to be trying to bring awareness about this. What you can say as a shorthand going forward if you want is that "releasing the source does not mean it's open source, which if it was would mean you had a protected right to actually build and run the software in question". That's both more correct, leads people to more information about the actual issue in question, and lets you offload some of the more complex explaining to the site made for it.
Or has this code been out there for a while?