Defining "Opposite"

How would you define opposite? It needs to be simple and understood by young kids. Here's what I've got so far:

Opposite = the most different

Give visuals. For example, have a hula hoop on the ground. You go on one side and the kid go on the "opposite" side. Have them move around the circle and you stay exactly opposite of them. Show them that if you are not directly across from them, you are different but not the most different. Then have them stay opposite from you as you move around the hoop.

Any thoughts on a good definition or teaching ideas?