Retching is a term used to describe a range of unpleasant physical reactions, such as NAUSEA, HEAVING, VOMITING, REGURGITATION, and SEASICKNESS. NAUSEA is a feeling of sickness or discomfort in the stomach, often accompanied by an urge to vomit. HEAVING is a strong, involuntary contraction of the chest muscles, usually accompanied by a retching sound. VOMITING is the forceful expulsion of the contents of the stomach through the mouth. REGURGITATION is the involuntary return of food from the stomach to the mouth. SEASICKNESS is a form of motion sickness caused by being on a boat or ship. All of these symptoms are associated with retching.