Waterbrash is a medical condition characterized by a sudden and excessive production of saliva, which is typically associated with acid reflux. In medical terminology, it is known as hypotonic regurgitation, but there are numerous synonyms that could be used in conversation or during a medical diagnosis. Some common synonyms for waterbrash include acid brash, acid saliva, sour regurgitation, and heartburn. Other medical terms that could be used interchangeably with waterbrash include gastroesophageal reflux disease (GERD), esophageal reflux, or simply reflux. It's important to note that waterbrash is not a disease in and of itself, but rather a symptom of an underlying condition, such as GERD or peptic ulcers.