Fact or Fiction,

Webster defines a fact as the following: 1 : a thing done: as a obsolete : FEAT b : CRIME c archaic : ACTION
2 archaic : PERFORMANCE, DOING
3 : the quality of being actual : ACTUALITY
4 a : something that has actual existence b : an actual occurrence
5 : a piece of information presented as having objective reality
- in fact : in truth

I guess my question is this, if said someone believes something was a fact no matter what the topic, even though they believe the occurnce happened or their is a hint of evidence even if they believe its wrong is it still a fact???