Hiatal: Pertaining to an hiatus, an opening. An hiatal hernia occurs when a part of the stomach protrudes through the diaphragm at the opening where the esophagus normally passes through the diaphragm. "Hiatus" in Latin means an opening. From Digestive Disorders Resources Side Effects From aHUS TreatmentWhat to Know When Ulcerative Colitis Gets WorseModerate to Severe UC: Targeted Solutions Featured Centers What Are the Best PsA Treatments for You?Understanding Biologics 10 Things People With Depression Wish You Knew