Free and open-source software
Free and open-source software (FOSS) is software available under a license that gives users the right to use, share, modify, and distribute the software – modified or not – to everyone and provides the means to exercise those rights using the software's source code. FOSS is an inclusive umbrella term encompassing free software and open-source software.
Source: Wikipedia — Free and open-source software (CC BY-SA 4.0)