I don't think this is a particularly good standard. If anything, I find startups at the very early stages (well before serious funding) the most interesting one

I don't think this is a particularly good standard. If anything, I find startups at the very early stages (well before serious funding) the most interesting ones to consider. What am I to call a company like this? The whole point is that it's a start--that's why it's a startup! I think the term should move in the opposite direction: consider even the most nascent of companies "startups", but stop calling large, well-funded and well-staffed companies like Twitter startups. There is far more difference between Twitter and a funded 10-person company than there is between that same 10-person company and a brand new two-person venture. Maybe it's a function of whom you talk to, but I've found the conversation about a startup does not proceed to "your funding, revenue, user base, that sort of talk". It proceeds to talking about your product, your idea and your technology. Sure, after that, people might ask about users and revenue, but they understand if that's in the future. On the other hand, if your idea or technology is sufficiently interesting, the topic often just stays on that. Now, if you're just writing an iPhone app with no real plans to grow it into a company, or you just started a project for fun, maybe you shouldn't call it a startup. But if you plan to grow and get significant funding or revenue, you are a startup--just maybe a temporarily inconvenienced one :).