/kəmˈpʌlsəri ||; kəmˈpʌlsərɪ/adj that must be done, by law, rules, etc 法例、规章等规定的；必须的；强制性的:
Maths and English are compulsory subjects on this course. 数学及英语是这个课程的必修科。It is compulsory to wear a hard hat on the building site. 在建筑工地内必须戴安全帽。 [SYN] obligatory 同义词为obligatory [OPP]Something that you do not have to do is non-compulsory, voluntary or optional. 自愿的用non-compulsory、voluntary或optional。