No. "Open Source" has a precise definition that includes terms of use:

https://opensource.org/osd

This is false.

Or do you mean in the specific context of the new usage of the term by AI companies, which totally contradicts the original usage?

Actually I think the definitions work (in practice) like this:

Open source means you can see the source, with a hint of other implications (which vary).

Source available means you can see the source, and is probably being used to exclude the extra implications of open source, but might not be.

Other terms exist and have unknown meanings and always will.

Now you're incorrect, just like before? :)

More seriously though, the word has a historically well-defined meaning, that lots of people put lots of time into defining really clearly, as others have linked to. It has precedence in courtrooms, lawyers have defined it, serious institutions have corrobated the existence of the meaning, etc etc.

You can choose to ignore that if you like, of course. You can argue for the word to be polysemic and have a new, second meaning, and you can even argue that the old meaning should be totally dropped and we just use this new meaning you're proposing.

But retroactively claiming that the word only ever had the meaning you say it has now is... odd, to put it politely.