Yes, to me luck is exactly that: the impact/outcome of uncertain or unpredictable circumstances. If they work out positively, then we say it was good luck, if negatively, then we say its bad luck. So luck is just a name for something that happens to us that we feel we didn't have any control over.
Which is also why many people believe we make our own luck: because in many situations that people attribute to luck, we can influence the outcome, consciously or otherwise.
I suspect luck is, in fact, simply the event of uncertainities crystallising favourably (or unfavourably if the luck is "bad"). Like it says in the dictionary.