Wake up, Ford Van Winkle

. This is the kind of talk your pedestaled degree-holders have to engage in and understand in order to get their degrees, and in order to truely understand the topic.
Read Webster's definition again and think about what it is actually saying. It's saying what he truth is: that phase is a continuum, one that is based upon a movement (rotation) as related to an original value, based upon a circular angular measurement. As such a continuum of measurement, there is no "inverse" value for phase as there is for polarity.
Let's say we arbitrarily say a non-linear waveform has an initial "phase value" of 0°. What is it's reverse phase? Before you answer, "180°", ask yourself what about -180°, 520º, and any other multiple that would result in an apparent inverse of polarity? What is the formula for "inverting phase" that yields a single correct answer to the question "what is the 'phase inverse' of waveform x?"
Or even more basic, but only to illustrate the point; what is the "inverse phase" of a waveform that exists entirely one one side of the center line of polarity? For example, a sine wave with an amplitude of 5 whose peaks range from -1 to -6. Rotate the phase of that wave 180° (i.e. "invert" or "reverse" the phase) in one instance and invert the polarity from negative to positive in another instance. Compare the results of those two instances and the results will be different.
Is "phase inversion" a slang term that's commonly used by audio engineers of all levels of education when what they really technically mean is polarity inversion? Of course it is. Do most of them understand what they really mean when they say that? Sure. I'm not arguing that, and I believe, neither is Benny.
What I am saying is that the common language does not reflect the science or the truth. Now, if it is you and I just talking shop about the last session one of us mixed, then yeah, I might be picking nits and arguing stupid semantics. But in a conversation regarding the actual explanation of just what "phase reverse" actually is all about, IMHO it's important that the misnomer is understood as such and that the differences be explained. For if they are not, it's just going to lead to further misunderstanding down the road, and in the next conversation, the rookie to the topic is going to inadvertantly be levaing their pants around their ankles and bending over, just waiting for the likes of the less tactless amongst us to call them idiots and berate them for not knowing what they're talking about.
G.