No its not. I've seen dozens of retailing operations in multiple countries. None use this term, which brings me smoothly to my next point...
>It refers to the value of the goods sold.
aka CoGS (Cost of Goods Sold) (or CoS in some regions). Unlike GMV you'll actually find that on the financial statement of major retailers. As I said:
>Must be some type of startup slang so to speak.
Would be curious to hear if there is some actual business reason that warrants giving this a new name in the startup context though...