It's hard to have a concrete definition of happiness.
I think that each individual has a different meaning of what happiness is.
I define happiness as,
The joy you feel in your heart.
The laughter you have among family and friends.
That great feeling of ardor when you're around that special someone.
A sense of true belonging.
Happiness is all these things, and probably more.
But I think there can be one worldwide meaning of happiness that everyone can agree to.
Which is something that can make your heart smile.