Even one of my go-to references for the region, "A Wine Atlas of the Langhe: The Great Barolo and Barbaresco Vineyards," published by Slow Food Editore, sheds no light beyond, "The derivation of this odd name is unknown...". So, what gives? Let's step back and take a look.
Pra di Pò is one of two accepted names, the other being Prapò, for a vineyard located toward the northern end of the eastern slope of the grand hill that forms the commune of Serralunga d'Alba, one of the primary villages of the Barolo region. Already losing you? Yep, I know it's tough to picture the lay of the land without actually standing there. Even Google Maps and Google Earth don't quite do the job, so you'll have to bear with me when it comes to directions and orientation. Or go to Serralunga and see for yourself.

Though the aforementioned "Wine Atlas" seems to suggest that "Pra di Pò" is the preeminent name for the site, looking at it from the wine perspective might lead one to think otherwise. To my knowledge, only the Ettore Germano estate, currently via its head man Sergio Germano, uses the "Pra di Pò" nomenclature, and then only for the Dolcetto that, after the 2008 vintage, will no longer be produced. Germano's cru Barolo from the same vineyard site is named "Prapò," as are all other wines I know of that bear the same cru designation, regardless of producer. (If I'm wrong about this, anyone, please let me know.)
For some time now, I've conjectured that the "Pra" part of "Pra di Pò" was a truncated version of the Italian word for meadow: "prato." It wouldn't be the first Italian wine I've encountered that follows that sort of naming convention, "Pradi___," or "meadow of (fill in the blank)." The question remaining — What does Pò mean? — continues to elude me, though. The river Po comes to mind but, though it does flow through Piemonte, it is not visible from Serralunga; an unlikely answer, it would seem.
In hopes of clarification, I turned to my man of the etymon, linguist extraordinaire Dr. Jeremy Parzen at Do Bianchi. Jar had this to say:
"A quick look at all my toponomastic references for Langa revealed only that "the origins of the strange name of this vineyard are unknown." [Sounds like we may be using the same reference manual.]That positioned before or first interpretation made sense to me, as it would seem to be a logical description of the position of Pra di Pò relative to its uphill neighbor, Cerretta, in relationship to the village of Serralunga itself. (Remember the photo above?) The problem is that such an interpretation assumes that Cerretta would have been held historically in some precedence above Prapò, something that I can not attest to prior to the modern era and that could even now be argued.
The philologist in me wants to think that praepositus (Latin, literally, positioned before or first) could be a possible etymon. And likewise, the linguist in me feels obliged to point out that pra di pò could be false etymology.
More often than not, the origins of these names are found blowing in the wind. Because the toponyms usual predate the abolishment of sharecropping in Italy, the ampelonyms commonly evolved through an oral tradition that defies and denies our desire to know the fons origo or original source of the words."
I've posed the same question(s) directly to Sergio Germano. If he's able to shed any clearer light on the matter, I'll be sure to report back. If not, and until then, I suppose the meaning of "Pra di Pò" will continue to be a mystery of linguistic history.
