butterball

noun3

1. •
   A round lump of a coagulated fat used in cooking such as butter or margarine.
2. •
   (slang, offensive) An overweight person.

   • What if your baby is a butterball? Does Fat-Proofing mean you should put your infant on diet?. — 1988
3. •
   A small North American duck, the bufflehead, Bucephala albeola.

   • The skipper had his eye on a bunch of butterballs feeding not far from the boat. In fact there were ducks all around — though he did not tell me so. — 1917