1. The part of a hollow organ of the body farthest from its opening; such as, the part of the eye's retina opposite the pupil.
2. In medicine, fundus refers to the bottom or base of an organ; examples include: the fundus of the eye (the retina), the fundus of the uterus, and so on.
3. The anatomical term referring to a portion of a bodily organ which is opposite of its opening.
4. The base of an organ or the part opposite to or remote from an aperture (opening).