If it means that to me and everyone else who uses the word in the same way, how can it not "mean that?" Because that's not what's in the dictionary? Because that's not what someone who lived 100, 50, 25 years ago would have meant when they said it?

I don't buy it. Language is defined by its usage, not the other way around. If I say "actionable" and everyone understands what I mean by it -- yourself included, if only begrudgingly -- then what does it mean if not the thing which everyone understands?