We need a new word. "Startup" has essentially become as meaningless as "agile". Semantically, "startup" is now just an umbrella under which the same paper-pushers and conference-call-bros we were trying to escape from are convening.
"A startup is a company designed to grow fast. Being newly founded does not in itself make a company a startup."
Wikipedia says a startup is "a partnership or temporary organization designed to search for a repeatable and scalable business model"[1]. The relevant Wiktionary entry defines it as a "new organization or business venture"[2], fairly similar to the OED's "newly established business" definition[3].
[1] https://en.wikipedia.org/wiki/Startup_company
[2] http://en.wiktionary.org/wiki/startup
[3] http://www.oxforddictionaries.com/us/definition/american_eng...
I think if we place emphasis on the word "scalable," PG + Blank's definitions are compatible. Both distinguish "startup" from "new company." I don't think most people would categorize building a tech company and starting a hair salon as the same activity because of the force multiplier of scale.