If something is compulsory, you must do it or accept it, because it is the law or because someone in a position of authority says you must.
双语例句
例： In East Germany learning Russian was compulsory.
在前东德，俄语是必修课程。
例： Many companies ask workers to accept voluntary redundancy as opposed to compulsory redundancy.
许多公司要求工人们接受自愿离职，而非强制性下岗。