Ask HN: When is a startup not a startup?

How do you know that a startup has come out of the startup phase? More importantly, how does a startup know that its not longer a startup?

a) time since it was established b) making sales c) hiring more people

No single criteria seems to yield the correct answer. It may take a startup years to launch their product, there are companies that make sales, do hirings and even make money yet classified as startups.