Kept, or meant to be kept, secret within a certain circle of persons; not intended to be known publicly
The newspaper claims a leaked confidential report by the government admits to problems with corrupt MPs.
Inclined to share confidences; (of things) making people inclined to share confidences; involving the sharing of confidences.
Sitting in front of the fire, they became quite confidential, and began to gossip.
Having someone's confidence or trust; having a position requiring trust; worthy of being trusted with confidences.
a confidential agent; a confidential servant; a confidential whisper