Luck is the opposite of skill, random "fortunae" which decides things. Some people believe certain actions (such as living a virtuous life) can improve your luck but at the fundamental level luck has nothing to do with skill
I saw this wacky hippie site once where they said that luck balances out through all lives you live or some other feel-good mumbo jumbo. They lost me after I realised they assumed people reincarnate.
Well if you are playing a board game and the person to start first is the person who throws a six and you throw a six on your first go then that is lucky in the sense that there was a 1/6 chance that you were going to throw a six and you did. So to me luck is succeeding against the odds however luck in terms of a lucky charm increasing the odds in your favour is ludicrous. Having said that I came across a bit of research recently that said you are more likely to succeed if you have a lucky charm that you believed in on the basis that if you believe you will succeed in something then subconsciously you will perform better at it. It also works the other way; if you believe you're going to fail at something then you will subconsciously perform badly.
Luck is interesting: as a roleplayer I take a sort of wide angle approach. In a sufficiently large sample size its all propability and while each individual roll of the die (or event) has a propabilistic determination that can't be swayed one way or another I still think there is luck. What can happen is that a small likelihood result can occour when a small percentage of outcomes is needed for success. Or similarly for failure. And when the range is less confined a more average result can occour. These ectremes occouring when you need them is "luck" for me; and is totally compatible with a probabilistic universe. Course if your a Newtonian or believe in an omniscient diety then there is no luck and no probability: only mechanics.
