That's the definition that PG uses but I don't think it's common to the world at large.
Usually the difference is between a first stage company and a self sustaining operation. Once revenue is enough to cover costs and the company can essentially run without outside funding it pretty much stops being a startup.
Definition on Investopedia: https://www.investopedia.com/terms/s/startup.asp
Re:Rejected from YC (Again)
by matt_the_bass on Thursday October 17, 2019 @07:21AM
(#21280845)
My company has always been under 20 people. We’ve developed some unique tech and are the industry leader in our sector. We’re 18 1/2 years old, yet everyone still calls us a start up. WE’RE NOT A START UP! We’re a small tech business.
http://www.paulgraham.com/growth.html
>A startup is a company designed to grow fast. Being newly founded does not in itself make a company a startup. Nor is it necessary for a startup to work on technology, or take venture funding, or have some sort of "exit." The only essential thing is growth. Everything else we associate with startups follows from growth.