- Zoology.
- the first portion of the vertebrate alimentary canal, extending from the pharynx and esophagus to the end of the stomach or gizzard and, in some animals, the anterior duodenum, functioning in the ingestion, temporary storage, and partial digestion of food.
- the first portion of the alimentary canal in arthropods and annelids, composed of ectodermal, chitin-lined tissue and usually comprising the pharynx, esophagus, crop, and gizzard.
- (in mammals) the upper part of the embryonic alimentary canal from which the pharynx, esophagus, lung, stomach, liver, pancreas, and part of the duodenum develop.
- the anterior part of the digestive tract of vertebrates, between the buccal cavity and the bile duct
- the anterior part of the digestive tract of arthropods
