Retch is an unpleasant reflex action that involves the involuntary contraction of the muscles in the stomach and throat, resulting in a strong urge to VOMIT. It is often accompanied by a gagging sound and can be caused by a variety of factors such as nausea, indigestion, or even a bad smell. VOMIT, which is also known as puke or throw up, is the act of forcefully expelling the contents of the stomach through the mouth. HEAVE is a synonym for retch and is used to describe the act of making a strong effort to VOMIT. GAG is a reflex action that is similar to retch, but is usually triggered by a foreign object in the mouth or throat, such as food or a finger.