know for a fact

To have definitive knowledge of something. I know for a fact that he cheats in cards! I saw the ace up his sleeve. My mom says she knows for a fact that I'm getting the internship at her company, but I won't believe it until the recruiter calls me.

Common Names:

Name	Pronounced	Usage
Saladin	SAL-ə-din (English), SAL-ə-deen (English)	History
Nerissa	-	Literature
Adorinda	ah-do-REEN-dah	Esperanto
Thais	-	Ancient Greek
Tzefanyah	-	Biblical Hebrew
Aris (2)	-	Dutch