B2If something is compulsory, you must do it because of a rule or law: Swimming was compulsory at my school.The law made wearing seat belts in cars compulsory.Court cases, orders and decisionsDuty, obligation and responsibilitycompulsorily
/-əl.i/adverb›Patients can now be compulsorily detained in hospital only under tightly drawn criteria.Court cases, orders and decisionsDuty, obligation and responsibility