reflux

noun
  1. The backward flow of liquid in a system, particularly the return of stomach contents into the esophagus, often causing discomfort known as acid reflux. noun
    After eating a large meal, she often experienced reflux, which caused a burning sensation in her chest.
    The doctor explained that his chronic cough might be due to reflux irritating his throat.
  2. In chemistry, the process of boiling a liquid so that any vapor is condensed and returned to the stock, often used in laboratory settings to heat reactions over a prolonged period without loss of solvent. noun
    The chemist set up a reflux apparatus to ensure the reaction mixture was heated continuously without losing any of the solvent.
    Refluxing the solution allowed the reaction to proceed at a constant temperature for several hours.