really

When something is really a certain way, its very or very much that way.

Example: I really want to see a film.

If something really exists or really happens, it does exist or happen.

Example: Are you really going to the show?

You can say "really?" when you are surprised.

Example: "He won yesterday." "Really?"

You can say "really" when you agree with something.

Example: "That girl talks about herself way too much." "Really. She's a nightmare."