confidential

confidential /ˌkɑːnfəˈdɛnʃəl/ adjective
confidential
/ˌkɑːnfəˈdɛnʃəl/
adjective
Britannica Dictionary definition of CONFIDENTIAL
1 
[more confidential; most confidential] : secret or private
2 
[more confidential; most confidential] : showing that you are saying something that is secret or private
3 
always used before a noun : trusted with secret or private information

— confidentially

adverb