What does 'Independent Contributor' mean?

You are a self-starter: you have the ability to take on a feature request from start to finish on your own. You have the talent of Senior level but you also have the ability to break down (and ask for) requirements and communicate effectively. When an important feature is coming up people want you to work on it!

I'm reading this as the next step above senior (ie: super senior)

Here it is, but it really does differ by organization.