1. a moral or legal requirement; duty
2. the act of obligating or the state of being obligated
3. (Law) law a legally enforceable agreement to perform some act, esp to pay money, for the benefit of another party
4. (Law) law
a. a written contract containing a penalty
b. an instrument acknowledging indebtedness to secure the repayment of money borrowed
5. a person or thing to which one is bound morally or legally
6. something owed in return for a service or favour
7. a service or favour for which one is indebted