1. in a way that is intended to be kept secret or private; not for public knowledge
2. in a manner showing trust or intimacy; as a confidant

Examples

• She told me confidentially that she was planning to resign.
• The doctor spoke confidentially with the patient about treatment options.
• He whispered confidentially that he had won the lottery.
• The company shared the data confidentially with its partners.
• She confided confidentially in her best friend about her worries.
• The information was shared confidentially among the board members.