required by law or a rule; obligatory 必须做的;规定的;义务的 compulsory military service. 义务兵役。 it was compulsory to attend mass. 弥撒是必须要参加的。 ■involving or exercising compulsion; coercive 强迫的,强制的 the abuse of compulsory powers. 强制权的滥用。
派生 compulsorily adverb compulsoriness noun 语源
early 16th cent. (as a noun denoting a legal mandate which had to be obeyed): from medieval Latin compulsorius, from compuls- 'driven, forced', from the verb compellere (see compel)