Not OP, but---I've been in software and OSS for a long time now, and I never knew this. I thought the term for that was Free Software.
In fact, looking closely at that definition, isn't practically nothing open source?
"Open-source software is computer software with its source code made available with a license in which the copyright holder provides the rights to study, change, and distribute the software to anyone and for any purpose."
I.e. public domain? Any other license lives precisely to limit those rights of distribution, no?
Anyway, just pedantry. I see your point. Learn something new every day.