Definition: Appendixing: This term refers to the appendage or appendicule of a bird's digestive system, located at its base and extending into the throat or mouth. It contains numerous glands and organs that help regulate digestion, circulate fluids in the body, and support metabolism. Definition: The appendixing is a medical concept in anatomy, specifically pertaining to the structure located near the back of the bird's throat called the appendicule. This anatomical structure plays a crucial role by regulating digestive enzymes and hormones, as well as absorbing nutrients from the food being ingested. Appendixing is not directly related to the appendix or appendixes of other organisms. It can be found in birds, mammals, reptiles, and even fish, though its specific function remains largely unexplored.