compulsory
/kəmˈpʌlsərɪ/adjective
1- 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。
1.1
- involving or exercising compulsion; coercive强迫的, 强制的：
the abuse of compulsory powers.
强制权的滥用。
派生词
compulsorily
adverbcompulsoriness
noun词源
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）.