obligation
/ˌɒblɪˈgeɪʃən/noun
1- an act or course of action to which a person is morally or legally bound; a duty or commitment（道义, 法律上的）义务（或责任）; 承诺：
with infinitive I have an obligation to look after her.我有义务照顾她。
1.1
- mass noun the condition of being morally or legally bound to do something（道义, 法律上必须做某事的）约束：
they are under no obligation to stick to the scheme.
他们不受必须恪守该方案的任何约束。
1.2
- a debt of gratitude for a service or favour恩惠, 人情债：
she didn't want to be under an obligation to him.
她不想欠他的情。
1.3
- Law a binding agreement committing a person to a payment or other action【律】（承诺付款等的）合同, 契约。
短语
day of obligation
- (in the Roman Catholic Church) a day on which all are required to attend Mass（罗马天主教）所有的人都必须参加弥撒的日子。
派生词
obligational
adjective词源
Middle English （in the sense 'formal promise'）： via Old French from Latin obligatio（n-）, from the verb obligare （see OBLIGE）.