What does Defying Gravity mean?

My last quick post of the day is why I named this blog Defying Gravitiy/Andreaisdefeyinggravity
It is from Wicked and I love the cover from Glee. But the words mean a lot to me,esp right now at this time in my life

"Kurt" and "Rachel" from Glee- Defying Gravity

Something has changed within me
Something is not the same
 I'm through with playing by the rules of someone else's game
Too late for second-guessing
Too late to go back to sleep
It's time to trust my instincts Close my eyes: and leap!
It's time to try defying gravity
I think I'll try defying gravity
Kiss me goodbye
I am defying gravity
And you wont bring me down!
I'm through accepting limits ''cause someone says they're so
Some things I cannot change
But till I try, I'll never know!
Too long I've been afraid of Losing love
I guess I've lost Well, if that's love
It comes at much too high a cost!
I'd sooner buy defying gravity
Kiss me goodbye I'm defying gravity
I think I'll try defying gravity
And you wont bring me down!
I'd sooner buy defying gravity
Kiss me goodbye
I'm defying gravity
I think I'll try defying gravity
And you won't bring me down!bring me down!ohh ohhh ohhhh!