Requirements arising from a person's situation or circumstances (e.g., relationships, knowledge, position) that specify what must or must not be done for some moral, legal, religious, or institutional reasons. For example, students have an obligation see their advisor on or before Registration Day. People have a moral obligation to keep their promises. Notice that usually statements of obligations specify what acts are required or forbidden without reference to the consequences of performing the act (except in so far as these consequences are a part of the characterization of the act itself - for example, killing is an act that results in death). However, occasionally you will see such statements as "engineers have an obligation in their work to ensure the public safety," which mean that engineers are morally required to ensure the public safety but which do not specify what acts they should or should not perform in order to ensure safety. A legal obligation is a legal requirement that specifies what types of actions are permitted, forbidden, or required on legal grounds. Often legal obligations are monetary debts. When we speak of an obligation without specifying its nature we will mean a moral obligation.

This definition is in context to Ethics. See more contextual defintions for Obligations.