Semi-free software, as defined by the Free Software Foundation, is software that is not free software, but comes with permission for individuals to use, copy, distribute, and modify (including distribution of modified versions) only for non-profit purposes. (Such software is also not open source according to the definition of the Open Source Initiative.)

PGP and Angband are examples of semi-free programs. The Free Software Foundation classifies semi-free software as non-free software, but draws a distinction between semi-free software and proprietary software.

References

• Semi-free software, definition by the Free Software Foundation