[dbaupp]

It’s used flippantly at times, but lock-free is a technical term referring to a guarantee of global progress https://en.m.wikipedia.org/wiki/Non-blocking_algorithm (I think it’s also sometimes used as a synonym for non-blocking, so including “obstruction-free” too).

For instance, if all threads except one are stopped, the single running thread should “finish” (for whatever finish means) in a finite time (lock-free is stronger than this condition, too). An algorithm using mutex-style locks fails this guarantee, if one of the stopped threads is inside the critical section.