What does AVA mean in the Wine World?

AVA= American Viticultural Area
An AVA is defined as "a delimited grape growing region, distinguished by geographical features, the boundaries of which have been recognized and defined"

Napa Valley was named an American Viticultural Area in 1983, making it the first AVA in California. Sonoma Valley, Carneros, Finger Lakes, Willamette Valley, and Columbia Valley are all AVA's. There are now more than 140 AVA's in the United States.

(The Rockpile AVA is an American Viticultural Area located in Sonoma County, California, northwest of the town of Healdsburg. It was established in 2002. It is aptly named after its demanding landscape.)