Vomiting or regurgitation is the sudden expulsion of vomit (the contents of the stomach) through the mouth. It is a mechanism for expelling ingested poisons, and may be triggered by stimuli which might indicate the possibility of poisoning, such as motion sickness, or sight of decayed food, or other people vomiting.
The feeling that one is about to vomit is called nausea.
Some Adult birds regurgitate food to feed their young. The food can be either incompletely digested or partially predigested, depending on the species.
Some bird species may also use regurgitation as a form of defense, vomiting when wounded or molested. When an intruder or a predator comes near a fulmar on its nest, the bird vomits oil up to 3 feet at the enemy.
Slang terms for vomiting: Throw up (phrasal verb), puke, barf, chunder, heave, boke, hurl, blow chunks, spew, upchuck.