nan·o·brew·e·ry (noun): A scaled-down microbrewery, often run by a solo entrepreneur, that produces beer in small batches.
in a recent article, the blog Top Fermented highlighted the trend towards nanobreweries, offering this definition: "There’s no good definition, but what seems to be settled upon is that you’re making an amount of beer, per batch, that is considerably less than one would expect from a production brewery: half-barrel or one-barrel systems are common and sometimes even less."
Hess Brewing Company, which calls itself "San Diego's first nanobrewery," puts the total output of nanobreweries at somewhere between 10 and 75 gallons.
A 2009 article on msn.com suggested that nanobrewing has emerged as part of the larger trend in food towards locavorism:
Unlike microbreweries, which are the thriving results of business models, nanobreweries are more entrepreneurial, with their creators doing it either as a high-profile hobby or as a stepping-stone to creating a bigger company. Either way, nanobrewing reflects the impact of neighborhoods, as these mavericks create a brew — and a following — one trench drain, one fermentation tank at a time.
The U.S. Department of the Treasury offers its own rough definition, while reminding budding nanobrewers that no matter how small their beer business, they are subject to federal taxation: