From Longman Dictionary of Contemporary Englishcompulsorycom‧pul‧so‧ry /kəmˈpʌlsəri/ ●●○ adjective MUSTsomething that is compulsory must be done because it is the law or because someone in authority orders you to → voluntary the threat of compulsory redundanciescompulsory schooling/education 11 years of compulsory education Car insurance is compulsory.► see thesaurus at necessary —compulsorily adverbTHESAURUScompulsory if something is compulsory, you must do it because of a rule or lawMaths and English are compulsory for all students.Compulsory education was introduced in 1870.Wearing a seat belt is compulsory.It is now compulsory for anyone claiming state benefit to register with a job centre.obligatory [not usually before noun] if something is obligatory, you must do it because of a rule or law. Obligatory is more formal than compulsoryIt is now obligatory for all competitors to wear face protectors.Evening dress is usual, but not obligatory.Military service is obligatory for all men between 18 and 27.mandatory if something is mandatory, you must do it because it is the law. Mandatory is more formal than compulsory and sounds strongerDrug smuggling carries a mandatory death sentence.In some countries, wearing helmets is mandatory for all cyclists.not compulsoryoptional if something is optional, you can choose whether to do it or notYou don’t have to do French – it’s optional.The holiday price includes optional excursions such as an evening cruise on the lake.General Studies is optional for sixth-form students.voluntary done because you want to do it and not because you have to – used especially about things that you do because you think they will help other people or be usefulThe programme is entirely voluntary, and no one will be forced to join.The charity is funded by voluntary donations.
Examples from the Corpus
compulsory• Thus, for Austen's heroine, Elizabeth Bennet, marriage was not just important, it was compulsory.• Attendance at the meeting is compulsory.• There are many benefits of compulsory competitive tendering in London, but many local authorities resisted it.• We will maintain our programme of compulsory competitive tendering of local authority services.• Maths and English are compulsory for all students.• It is now compulsory for anyone claiming state benefit to register with a job centre.• The study of Shakespeare is compulsory for major and joint programmes.• Smoke detectors are compulsory in all new buildings.• All young men are required to do two years of compulsory military service.• This amounts to compulsory purchase, but holds out the prospect that the shares will rise.• I suspect this, like compulsory religious education, gave me a lifelong scepticism about obligatory elements in any curriculum.• They pushed for state laws on compulsory sterilization of criminals and the physically defective, with some success.compulsory schooling/education• A child who lives in a state that requires school attendance must attend some acceptable school during the years of compulsory education.• Parents usually keep their children at home for a couple of years after they have completed their six years of compulsory education.• The State advances two primary arguments in support of its system of compulsory education.• The use of education services has become more equal during the years of compulsory schooling.• This will help pupils to develop a personal love of reading which will continue after compulsory schooling.• Are students exempt from compulsory schooling or from certain courses in the curriculum on religious grounds?• The law which makes Work Experience possible for young people in their last year of compulsory education specifically forbids their receiving payment.From Longman Business Dictionarycompulsorycom‧pul‧so‧ry /kəmˈpʌlsəri/ adjective something that is compulsory must be done according to a law or ruleThe company has introduced compulsory overtime for all its workers. 