hydrochloric acid Solution of hydrogen chloride (HCl) gas in water. It is obtained by the action of sulphuric acid on common salt, as a byproduct of the chlorination of hydrocarbons, or by combination of hydrogen and chlorine. Hydrochloric acid is used in industry and is produced by humans cells in the stomach lining to allow the enzyme pepsin to digest proteins.

hydrochloric acid A strong acid, HCl, that is produced by oxyntic cells in the wall of the stomach and forms a constituent of gastric juice. Hydrochloric acid is required for the conversion of pepsinogen to pepsin in the lumen of the stomach and kills various microorganisms that enter with food.

hy·dro·chlo·ric ac·id / ˌhīdrəˈklôrik/ • n. Chem. a strongly acidic solution of the gas hydrogen chloride, HCl, in water.

hydrochloric acid (hy-drŏ-klor-ik) n. a strong acid present, in a very dilute form, in gastric juice. The secretion of excess hydrochloric acid by the stomach results in the condition hyperchlorhydria.