gizzard

noun2

1. •
   A specialized organ constructed of thick muscular walls found in the digestive tract of some animals, including archosaurs (including crocodilians and birds), earthworms, some gastropods, some fish, and some crustaceans, and used for grinding up food, often aided by particles of stone or grit.

   • As fortune has it, kingbirds, like owls, lack a grinding gizzard and regurgitate hard fragments from their meals. — 2016
2. •
   (slang) The (human) stomach.

   • "Pushing a man's face into his own breakfast is beyond rules or reason, and deserves a punch in the gizzard." — 1918