A Fundus

(anatomy) the large, hollow part of an organ farthest from an opening; especially

1. the top, hollow portion of the uterus and
2. the back, interior part of the eye, accommodating the retina and associated blood vessels, etc.
3. the uppermost hollow of the stomach, which in humans forms a bulge above where the oesophagus enters the stomach.
4. the deepest part of a sulcus, such as the sulci in the human cerebral cortex.