It meets the original definition of open source as in the source code is open and modifiable, you know the opposite of closed source.
If you mean the OSI definition of open source which defines how free the licence is, rather than how open the source code is then I suggest you check out the FSF they are the original OSI and advocate for free software and generally don't feel the need to change an existing definition and make it theirs.
If you have the code to modify then its open source, thats all that open source is it has nothing to do with the license unless you are talking about an OSI license in which case its just an OSI license and nothing to do with the source code or its openness.
If you mean the OSI definition of open source which defines how free the licence is, rather than how open the source code is then I suggest you check out the FSF they are the original OSI and advocate for free software and generally don't feel the need to change an existing definition and make it theirs.