I agree that "unique problem" probably isn't a good enough descriptor, but there's no such thing as something that's "legally" a startup or not. Now, there are

I agree that "unique problem" probably isn't a good enough descriptor, but there's no such thing as something that's "legally" a startup or not. Now, there are regulations that define a "small business" based on number of employees or revenue, so you can say that you can be "legally" a small business. But startup is another animal. I personally prefer Steve Blank's definition.