Well, there's two parts to this question really. What makes a newly founded company a startup in the first place, and when does such a company stop being a star

Well, there's two parts to this question really. What makes a newly founded company a startup in the first place, and when does such a company stop being a startup? The other comments addressed the first part (scalable business centered on growth), but the second part is a bit more nebulous. pg gave an off the cuff answer at YC's Work For a Startup day which was pretty insightful: "When politics starts working."