(n.) One to whom secrets are entrusted\.

Dutch uncle Polonius acquaintance admonisher adviser advocate alter ego amigo backer backseat driver best friend bosom friend brother buttinsky casual acquaintance close acquaintance close friend confidante consultant counsel counselor expert familiar favorer fellow fellow creature fellowman fidus Achates friend guide inseparable friend instructor intimate kibitzer lover man Friday mate meddler mentor monitor neighbor nestor orienter other self partisan pickup preceptist repository right hand right-hand man second self strong right hand supporter sympathizer teacher well-wisher