Dumplings are actually Calzones according to The Cube Rule

I’d call it a moist doughy savory lump. Could be steamed or boiled.

Wikipedia has:

https://en.wikipedia.org/wiki/Dumpling

Dumplings are a broad class of dishes that consist of pieces of cooked dough (made from a variety of starchy sources), often wrapped around a filling. The dough can be based on bread, wheat or other flours, or potatoes, and it may be filled with meat, fish, tofu, cheese, vegetables, or a combination. Dumplings may be prepared using a variety of cooking methods and are found in many world cuisines.

Largely, a dumping isn’t defined so much by what it’s made of, as it is how it’s cooked.

Dumplings need to be steamed or boiled as their initial cooking method.

Beyond that, they have to be made of some variation of dough.

Dough is usually limited to grain flour of some kind mixed with a liquid and possibly fats; seasoning is optional, though salt is almost always included.

I’m not sure a dough without a grain based flour would be able to perform the same way, but I still learn new things about ingredients regularly, so I’m not willing to say it isn’t possible. That being said, there are other words that cover the rough equivalent made of meat as a primary ingredient, and meats won’t allow you to form a wrapping that will fill the roll of wrapped type dumplings. Yeah, you could wrap something in sliced meat, but that isn’t a dumpling; other words exist for that, and it doesn’t work the same.

Here in the US, the biggest debate about dumplings is noodles vs soggy biscuits. Noodles are sometimes called dumplings when using something like store bought egg noodles, and I will fight over that not being dumplings. “Noodle” dumplings would have some amount of liquid other than eggs, be thicker, and don’t actually look like noodles much.

Basically “Noodle” dumpling are unleavened biscuits. They don’t rise at all. They may swell, but don’t generate air bubbles to “puff” up. If you aren’t using that kind of dough, then calling it a dumpling is honorary, but you’ll disappoint anyone you invite over fir chicken and dumplings. So no regular noodles, that’s chicken noodle soup/stew.

Soggy biscuits, however, rise. You can take any american style biscuit dough, spoon (or otherwise measure out) your preferred size dumpling into hot water, and you’ve got a basic soggy biscuit dumpling. Milk, water, buttermilk, nut milks, whatever liquid it calls for in your recipe is fine. But it will be chemically leavened since once you use yeast, it isn’t a quickbread, and all us style biscuits are quickbreads. You use yeast, it’s a roll or bun.

And all of that ignores filled dumplings. Filled dumplings use a variety of doughs, but they will be unleavened because if the dough can rise, it’ll break during cooking as thin as it has to be to wrap stuff with it. Which means they aren’t really “filled” in most varieties, but nobody cares when you say ravioli is a filled pasta, so why would that matter with dumplings.

And, yes, by the above definitions, ravioli are a dumpling. Barely, and I wouldn’t be willing to fight over that, but still.

a filling encased in pastry and cooked by poaching, steaming, frying, or baking

but, caveat: the filling can be more pastry

empanadas are dumplings
pierogis are dumplings matzo balls are dumplings
gyoza are dumplings
tortellini are dumplings

A little pocket of dough filled with a mixture of other ingredients.