Any software is considered free software so long as it upholds the four essential freedoms:

1. The freedom to use the software for any purpose.
2. The freedom to study and improve the software.
3. The freedom to share the software.
4. The freedom to collaborate on the software.

Software which upholds these freedoms is free software. Software which does not is non-free.

writefreesoftware.org

About Free Software

Source