The phrase "frozen dumplings" refers to dumplings that have been prepared and then frozen, so they can be stored for a longer time and cooked later when needed. Full definition
Or, freeze the dumplings on a tray and transfer them into freezer bags once hardened. (honeytanie.com)
After filling all the dumplings put the tray in the freezer and freeze the dumplings for about an hour. (theindigokitchen.com)
If you don't want to cook immediately, freeze them in a single layer, and then remove from baking sheet and store frozen dumplings in ziplock bag. (arthurstreetkitchen.com)