Taleb has an amazing book on this very interesting concept - the opposite of fragile. No, it's not strong or resilient - which implies ability to fight and survive stress and negative situations. Anti-fragile is the ability to thrive in adversity. What an amazing quality to have!
Dhoni is one example. He loves stress, tension. Remember the world cup? Remember how he was down in the dumps just a few weeks back, and how he has bounced back so strong, he is now literally untouchable?
Social unrest is also anti-fragile. The more governments suppress it, the more they get stronger.
Am I anti-fragile? Are you?