acid reflux

noun

: backward flow of the acidic contents of the stomach into the esophagus that is due to malfunctioning of a sphincter at the lower end of the esophagus and that results especially in heartburn : gastroesophageal reflux

a medication for acid reflux

Acid reflux is the backflow of stomach contents into the esophagus. The feeling of acid reflux is heartburn: a mild burning sensation in the mid-chest …

—The Tennessee Tribune

Acid reflux occurs when the valve between your esophagus and stomach doesn't close properly, allowing stomach acid to wash back up through your esophagus …

—Miriam Jones Bradley

Examples of acid reflux in a Sentence

Recent Examples on the Web

Elderberry helps the digestive system For digestive issues like acid reflux, indigestion or even extreme constipation, elderberries can be a fantastic solution and keep your gut healthy. — Bestreviews, Chicago Tribune, 4 Sep. 2026

And those who are pregnant or have conditions such as diabetes, acid reflux, irritable bowel syndrome or a tendency toward low blood sugar may require even more individualized guidance. — Daryl Austin, USA Today, 2 Sep. 2026

Improved Digestion Bloating, constipation, acid reflux, upset stomach—all are uncomfortable signs of indigestion after eating. — Audrey Noble, Vogue, 20 Aug. 2026

Overnight, this 54-year-old Southern Californian began dealing with acid reflux, random bloating, constipation, and a rebelling digestive system that suddenly despised her favorite foods. — Cheryl Fenton, Flow Space, 17 Aug. 2026

Word History

First Known Use

1960, in the meaning defined above

Medical Definition

acid reflux

noun

: backward flow of the acidic contents of the stomach into the esophagus that is due to malfunctioning of a sphincter at the lower end of the esophagus and that results especially in heartburn : gastroesophageal reflux

… people who report experiencing at least weekly symptoms of acid reflux have substantially higher risks of BE [=Barrett's esophagus] than those with less frequent episodes. Moreover, we found that symptoms of acid reflux experienced at older ages conferred substantially higher risks of BE than symptoms at younger ages …

—Kylie J. Smith et al., Cancer Epidemiology, Biomarkers & Prevention