One thing in the entire world is both real and imaginary. What is it?

fiction

I don't suppose you're referring to 'complex numbers' in mathematics?

A dream?

I guess y'awl have waited long enough. Look at my name and you'll find it - 0 - zero!

'Fuse, you have thrown me a curve here. Every time I try to argue fiction is or is not, I get all tangled up. The only imaginary part is what happens in the reader's mind - do you agree?. That being said, Tree is also right, right?

Catty, this is a great math trivia question. Zero is the only number that fits a mathematician's definitions of both real and imaginary numbers.