Freedom is such a vague word, we shouldn’t use this word if we want to be precise about what we mean by it.
When we talk about free software, we point to transparency, studyability, tinkerability and sharability. The openness to allow ourselves to use our tools with freedom.
However, I do not think we should use the term open source. The reason for my distancing of the word source is because the word makes us think about development instead of the end user. Because if we want these kinds of software to appeal to the masses, we the word to emphasize that it is meant for them. Instead, I would use the term open software, open tool or open machine.
That really depends on what you’re trying to convey.
“Open source” is all sbout the code, and it usually implies that it can be used for any purpose, commercial or otherwise. When I think of open source, I think of MIT, BSD, and other permissive licenses where the point is to ensure the source can be used for any purpose.
“Free software” is all about the users, and it comes with extra baggage that ensures that users will always have access to improvements by others. If it’s used in a commercial project, you can demand the improvements be made available under the same terms as the library it’s based on. When I think of free software, I think of copyleft licenses like GPL, AGPL, etc.
Both are valid, and generally all free software is open source but not all open source software is free software. Both are worthwhile terms, just be careful to lump non-free software (e.g. pretty much anything not copyleft) with free software if that’s what you prefer.