"Important"

George has asked me twice, "What does 'important' mean?"

I've struggled to find words to explain this to George, but obviously I'm failing to convey the meaning since he continues to ask what it means.

Finally, I resorted to the dictionary this morning.  The definition I read to him was "of great significance or value; likely to have a profound effect on success, survival or well being."  Understandably, I received a blank stare in return.  I also tried to explain that he likes his cars a lot and they mean a lot to him because he wouldn't want anything to happen to them, so that means they are important to him.  He still seems confused.

Anyone else have an idea of how to explain the word "important" to a three-year old?