English definition of “fact”
TRUE THING [C] › something that you know is true, exists, or has happened: I'm not angry that you drove my car, it's just the fact that you didn't ask me first. No decision will be made until we know all the facts. He knew for a fact (= was certain) that Natalie was lying.
REAL THINGS [U] › real events and experiences, not things that are imagined: It's hard to separate fact from fiction in what she says.
in fact/in actual fact/as a matter of fact › used to emphasize what is really true: I was told there were some tickets left, but in actual fact they were sold out. › used when giving more information about something: "Is Isabel coming?" "Yes. As a matter of fact, she should be here soon."
the fact (of the matter) is › used to tell someone that something is the truth: I wouldn't usually ask for your help, but the fact is I'm desperate.