http://en.wikipedia.org/wiki/Vomiting

Vomiting (known medically as emesis and informally as throwing up and by a number of other terms) is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. Vomiting can occur due to a wide variety of conditions; it may present as a specific response to ailments like gastritis or poisoning, or as a non-specific sequela of disorders ranging from brain tumors and elevated intracranial pressure to overexposure to ionizing radiation. The feeling that one is about to vomit is called nausea, which usually precedes, but does not always lead to, vomiting. Antiemetics are sometimes necessary to suppress nausea and vomiting. In severe cases, where dehydration develops, intravenous fluid may be required.