Definitions of fact:

• noun:   a piece of information about circumstances that exist or events that have occurred

  Example: "First you must collect all the facts of the case"

• noun:   a concept whose truth can be proved

  Example: "Scientific hypotheses are not facts"

• noun:   a statement or assertion of verified information about something that is the case or has happened

  Example: "He supported his argument with an impressive array of facts"

• noun:   an event known to have happened or something known to have existed

  Example: "Your fears have no basis in fact"