1.NounA drug C16H14F3N3O2S that acts as a proton pump inhibitor to reduce gastric acid secretion and is administered orally in the treatment of heartburn associated with gastroesophageal reflux disease and to promote healing of acid-related erosive esophagitis. It is the dextrorotatory enantiomer of lansoprazole and is marketed under the trademark Dexilant.