I intentionally didn't use a well defined term as it would miss the point.
There is all kind of somehow "open" software which might be OSI open source or even be GPL licensed but is de-facto not free software.
Like I have seen more then one case where GPL or similar was used to archive "open sourcing the software" while "making sure no on complying with law can benefit relevantly from it". E.g. publish a software under GPL which is strongly dependent all through the stack on some proprietary software which is GPL incompatible but has some pseudo decoupling though some interfaces. The company which wrote the software just uses a different license when they use it. Everyone else would have to spend impractical amounts of time to create adapters to make it actually usable under the GPL license. Sometimes not much less time then rewriting it from scratch. I have seen this pattern quite often. Through more often with AGPL then with GPL. Sometime it did feel that such theoretically but not practically free software likes (A)GPLv3 more the actually free software does like it (but I'm pretty sure this is a bubble).
There is all kind of somehow "open" software which might be OSI open source or even be GPL licensed but is de-facto not free software.
Like I have seen more then one case where GPL or similar was used to archive "open sourcing the software" while "making sure no on complying with law can benefit relevantly from it". E.g. publish a software under GPL which is strongly dependent all through the stack on some proprietary software which is GPL incompatible but has some pseudo decoupling though some interfaces. The company which wrote the software just uses a different license when they use it. Everyone else would have to spend impractical amounts of time to create adapters to make it actually usable under the GPL license. Sometimes not much less time then rewriting it from scratch. I have seen this pattern quite often. Through more often with AGPL then with GPL. Sometime it did feel that such theoretically but not practically free software likes (A)GPLv3 more the actually free software does like it (but I'm pretty sure this is a bubble).