A fact that has been shown not to be true is an example of something that has been disproven.
The theory devised by the young inexperienced research scientist was easily disproven.
The idea that the earth is flat can easily be disproven thanks to both the modern laws of physics and satellite imagery.
If a theory continues to be disproven, can it become a fact?
Jane was not happy with the results of her medical exam, so she hoped the diagnosis would be disproven by another doctor.
Breast cancer has never been conclusively proven or disproven as a cancer caused by birth control pills.