What is the function of だろう?


I've seen a question:

> なんで **だろう** ？

I know that なんで means 'why'. So what about だろう?




だろう is a short form of でしょう ("one supposes").  
Hence I read "なんでだろう" as "I wonder why" or "Why, do you suppose?"




だろう is a short form of でしょう ("one supposes").  
Hence I read "なんでだろう" as "I wonder why" or "Why, do you suppose?"

