When it comes to describing something that is an undeniable truth, the term "absolute fact" is commonly used. However, there are many other synonyms that can be used to describe the same concept. Some of these include "undeniable evidence", "indisputable truth", "certainty", "undeniable reality", "verifiable fact", "incontrovertible certainty", "established truth", "irrefutable conclusion", "verified authenticity", and "undeniable proof". All of these synonyms indicate something that cannot be denied or refuted, and are useful for expressing the importance and relevance of a particular piece of information to a wider audience.