@wholemilk The biggest problem with "FOSS" is that most people will only ever understand it to mean gratis, source-available software, plus most people who understand the intended meaning say free software or libre software instead.
Many people have heard of "open source" existing, but in 99.95% of cases, the only natural meaning of "the source code is publicly available" is assumed and few people have ever seen the OSD; https://opensource.org/osd (warning; there is proprietary JavaScript on that website).
"FOSS" is a combination of both free software and "open source" software, in an attempt to be neutral and resolve confusion, but it fails to be neutral and makes for a worse confusion.
"FLOSS" ("free, libre and open source software") is neutral and at least may induce someone to punch "libre software" in a search engine, but otherwise it has the same problems as "FOSS".
@mangeurdenuage wasn't really making a joke, he was pointing out that rms is not pleased if he's branded as "the father of open source", or "FOSS", as he only does free software.
@mangeurdenuage I understood the difference between FOSS and OSS. I said FOSS initially (which I understand to mean Free and Open Software), and I understand FOSS to be synonymous with Freedom respecting software. Maybe this is inaccurate.