commissar UK /ˌkɒmɪˈsɑː/US /ˈkɑ.məˌsɑɹ/ noun3 •(informal, humorous) A political functionary whose job is to push the party or government line. •(historical) An official of the Communist Party, often attached to a military unit, who was responsible for political education. •(historical) The head of a commissariat. formscommissars