is an English expression borrowed from Latin. It means authentic, genuine, real, legitimate,
. When it is used as an adverb it means in good faith, without intention to deceive
. The concept of good faith was very important in ancient Rome, since it was always assumed that citizens would never act in a way to hurt others, unless they weren’t aware of doing so.
The correct pronunciation in Latin is different though: click and listen to the pronunciation of Bona fide in Latin