When is a viral a viral and not a viral?

I was asked to work on ideas for a viral project.

Now if you call a project a viral, and it doesn't get sent around then is it still a viral?

If it does succeed and gets sent around then is it just a successful viral as opposed to an unsuccessful one?

Can you call a project a viral,, or is viral just the process an idea goes through after you have made it?

I guess the point I'm trying to make is, can you be doing a viral project, or is viral just the second string of the vehicle?