Luck (noun)

1. Success or failure apparently brought by chance rather than through one's own actions.
2. A force that is believed to operate for good or ill in a person's life.
3. A combination of events, circumstances, etc., operating by chance to bring good or ill to a person.

Origin:

Middle english (originally in the sense "happenstance, fortune"): from old norse leikr, of germanic origin.

Examples:

1. She attributed her success to hard work rather than to luck.
2. We're going to need a lot of luck if we're going to win this game.
3. He had the luck to be in the right place at the right time.
4. Good luck charm brings hope to someone in need.
5. Her luck changed when she won the lottery.