n. phr. Something that is really true; something that can be proved. The town records showed that it was a matter of fact that the two boys were brothers. It is a matter of fact that the American war against England was successful. Often used for emphasis in the phrase "as a matter of fact". I didn't go yesterday, and as a matter of fact, f didn't go all week. Mary wasn't wearing a blue dress. As a matter of fact, she hasn't got a blue dress.
Compare: FOR THAT MATTER, IN FACT.
Antonym: MATTER OF OPINION.