I don't think it does, but "open source software as defined by the Open Source Initiative" does have legal meaning.
Equally, "free software" does not have a legal meaning either, but "free software as defined by the Free Software Foundation" does.
That said, Stallman is probably right, the term "open source" cooked up by Perens et al was language used to mollify business people who feared the term "free software" (and "copyleft"... and Stallman). The term got traction and the popularity of the software greatly increased. But, by using this ambiguous phrase to describe software that you not only have the right to see the source of, but also to modify and redistribute, it opens the door to shysters who would try to claim that "source available" is somehow "open source"... because the "source" is "open".
I don't think it does, but "open source software as defined by the Open Source Initiative" does have legal meaning.
Equally, "free software" does not have a legal meaning either, but "free software as defined by the Free Software Foundation" does.
That said, Stallman is probably right, the term "open source" cooked up by Perens et al was language used to mollify business people who feared the term "free software" (and "copyleft"... and Stallman). The term got traction and the popularity of the software greatly increased. But, by using this ambiguous phrase to describe software that you not only have the right to see the source of, but also to modify and redistribute, it opens the door to shysters who would try to claim that "source available" is somehow "open source"... because the "source" is "open".