Fundus: In medicine, the bottom or base of an organ. For example, the fundus of the eye is the retina. However, the fundus of the stomach is inexplicably the upper portion. From the Latin for 'the bottom.' SLIDESHOW Heart Disease: Causes of a Heart Attack See Slideshow From Healthy Resources 10 Rheumatoid Arthritis SymptomsWhat Is Exocrine Pancreatic Insufficiency?Truth About Vitamin B12 Featured Centers Good and Bad Foods for PsoriasisVideo: Getting Personal on Life With MS Health Solutions From Our Sponsors Shot-Free MS Treatment Your Child and COVID-19