B2[C or U]the fact that you are obliged to do something: [+ to infinitive]If you have not signed a contract, you are under no obligation to(= it is not necessary to) pay them any money.You have a legal obligation to(= the law says you must) ensure your child receives a proper education.Duty, obligation and responsibility›[C]something that you must do: I haven't got time to do his work for him - I've got too many obligations as it is.Duty, obligation and responsibility