n. A technology company that is less than ten years old and worth more than one billion dollars.

Example Citations:
What’s more, the number of $100 million plus funding rounds last year doubled compared to 2010, and one much-buzzed-about report shows there are more than two dozen tech startups valued at more than $1 billion. There’s even a new catchphrase for such startups, which include Dropbox, Uber and Snapchat: “unicorns,” denoting both their rareness and their dazzling promise.
—Peter Delevett, “Venture capital looks to be in a full-blown recovery — but is it too much, too soon?,” San Jose Mercury News, February 7, 2014

Forget the $1 billion “unicorns” out there — the last year has been all about the rise of the $10 billion companies — both Dropbox and Chinese mobile hardware company Xiaomi both had rounds at $10 billion valuations, raising hundreds of millions of dollars.
—Lauren Hockenson, “Airbnb reportedly set to raise up to $500M at $10B valuation,” Gigaom, March 20, 2014

Earliest Citation:
We found 39 companies belong to what we call the “Unicorn Club” (by our definition, U.S.-based software companies started since 2003 and valued at over $1 billion by public or private market investors). ...

On average, four unicorns were born per year in the past decade, with Facebook being the breakout “super-unicorn” (worth >$100 billion).
—Aileen Lee, “Welcome to the Unicorn Club: Learning From Billion-Dollar Startups,” TechCrunch, November 2, 2013

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