I mostly say "software freedom", but I alternate between "free software" & "opensource" because I don't want to be in that decades-old new-true-scottsman argument.
I don't consider "Linux" to be a reasonable way to demarcate operating systems, & I think grouping all this choice under a single brand is actively harmful to our growth. If I want to generalize I find "freedesktop" suits my needs well. I say "Linux" regarding hardware support & the mechanations of how that piece works.
alcinnz