mandatory mandatory /ˈmændəˌtɔri/

adjective

1. () Required by rule  ( compulsory , required , mandatory )
   required by rule
    In most schools physical education is compulsory
   in most schools physical education is compulsory
    Attendance is mandatory
   attendance is mandatory
    Required reading
   required reading
   

noun

1. A territory surrendered by Turkey or Germany after World War I and put under the tutelage of some other European power until they are able to stand by themselves  ( mandate , mandatory )
   a territory surrendered by Turkey or Germany after World War I and put under the tutelage of some other European power until they are able to stand by themselves
   
2. The recipient of a mandate  ( mandatary , mandatory )
   the recipient of a mandate