define celiac
celiac disease in Medicine Expand. celiac disease n. A malabsorption disease characterized by sensitivity to gluten and atrophy of the mucosa of the upper small intestine, manifested by diarrhea, steatorrhea, and nutritional and vitamin deficiencies. Also called gluten enteropathy, nontropical sprue. celiac disease. A gastrointestinal disease characterized by an inability to absorb the protein gluten, resulting in diarrhea, the passage of stools having a high fat content, and nutritional and vitamin deficiencies.