Personally I think the term startup is overused. I regularly see simple premium membership sites paraded around as startups in all the startup news feeds.
I work for a small company (less than 20 people including contractors) that has been in business for 16 years. When I left my giant-ass defense contractor job to come here, a couple people there insisted on referring to it as a "startup". It is rapidly becoming a word that means whatever the speaker wants it to.