We had a recent thread here that started to address this issue, but got a bad start. I propose that intonation is the art/science of comparing of tones to a reference. That reference can be a tuner or other instruments. When we talk about intonation, much more comes up based on the frame of reference. We can refer to a fixed scale that could be used for tuning a piano for instance, or a dynamic relationship based on what happens when playing in an ensemble. We can also talk about balancing chords for the best "effect". What do you all think? As I discovered in the other thread, there are terms that some prefer to be used in a particular way. If we run into a situation, we simply need to ask for the definition and perhaps debate its merit. Mathematical formulas are OK, just remember that the audience is not primarily engineers.