obligation

noun

1. the social force that binds you to the courses of action demanded by that force"we must instill a sense of duty in our children"
2. the state of being obligated to do or pay something"he is under an obligation to finish the job"
3. a personal relation in which one is indebted for a service or favor
4. a written promise to repay a debt
5. a legal agreement specifying a payment or action and the penalty for failure to comply