Fixed fact

a well established fact.

See also: Fixed

References in classic literature ?
The bare little farmhouse was a fixed fact, but she had many a palace into which she now and then withdrew; palaces peopled with stirring and gallant figures belonging to the world of romance; palaces not without their heavenly apparitions too, breathing celestial counsel.
On Tribunal indictment, Haber said that they shall not accept an indictment if not based on evidence and fixed facts.
Our answers are ever-evolving, ever-tentative, just as science emphasizes working hypotheses over fixed facts.
The first subproblem is optimal setting of FACTS parameters and the second subproblem is OPF with fixed FACTS parameters.
The opportunity to disappear into the tall uncut has existed so long that we unconsciously assume it, like the wind and sunset, to be one of the fixed facts of Nature.