[Chrono]

An estimated value of $100b, the ability to throw $1b into acquisitions and over 3000 employees - still a startup?

By such logic you can almost call Google a startup, or any other IT firm really. What exactly makes Facebook a startup by any definition?

[staunch]

The valuation of a company is irrelevant to my definition of a startup. I think Facebook is still a startup because it's still in the process of rapidly scaling and transforming itself.

When it slows down and settles into long term strategy it will cease to meet my definition. It's starting to do that now.