1. A very very smart person who is always right.
2. A person who can't stand beeing wrong. Even if that person is wrong, he will just make the world change for him to be right.
3. Someone who knows all kinds of stuff, and he is very good at calculating.
1. He's so smart, he's a yann.
2. Urgghh. He was the one who was wrong, but he made it look like I was wrong. That yann-guy is so annoying.
3. Wow. He just calculated 3047238+87236745 using only his brain, and the answer was right! what a yann!