dos ‧ si ‧ er /ˈdɒsieɪ $ ˈdɒːsjeɪ, ˈdɑː-/ BrE AmE noun [countable]
[ Date: 1800-1900 ; Language: French ; Origin: 'set of documents with a label on the back' , from dos 'back' ]
a set of papers containing detailed, usually secret information about a person or subject SYN file
dossier on
A firm of detectives produced a dossier on his activities.