[adjective] [not gradable] [formal] - which must be done, or which is demanded by lawThe minister is calling for mandatory prison sentences for people who assault police officers.Athletes must undergo a mandatory drugs test before competing in the championship.In 1991, the British government made it mandatory to wear rear seat belts in cars.
MANDATORY
Meaning of MANDATORY in English
Cambridge English vocab. Кембриджский английский словарь. 2012