The term "lucky winner" refers to someone who has won a prize or contest by chance, often through some form of random selection. The implication is that this person was fortunate enough to be chosen from among many others and received something valuable as a result - whether it's money, a prize, an opportunity, or simply the satisfaction of having their lucky numbers drawn in a lottery. In other words, being called a "lucky winner" means that someone has experienced good fortune through happenstance rather than by any effort or skill on their part.