Attack of the Slashes Part II: Probability/Possibility vs Possibility/Probability

[Parsons]

I always took possibility/probability to mean that something was in the realm of possibility to happen, while taking probability/possibility to be the most likely outcome. That being said, I'm not sure if probability/possibility would then be just the most likely outcome in a 'major' set of outcomes (ie there are 6 most probable outcomes with the lead being 20%), or if there is some threshold to calling it probable/possible (such as greater than 50%).