English▸ noun an act or course of action to which a person is morally or legally bound; a duty or commitment:
[with infinitive] I have an obligation to look after her
he has enough cash to meet his present obligations.
▪ the condition of being morally or legally bound to do something:
they are under no obligation to stick to the scheme.
▪ a debt of gratitude for a service or favor:
she didn't want to be under an obligation to him.
▪ Law a binding agreement committing a person to a payment or other action.
– ORIGIN Middle English (in the sense ‘formal promise’): via Old French from Latin obligatio(n-), from the verb obligare (see oblige).