Definitions
1.NounThe act of binding oneself by a social, legal, or moral tie to someone.
2.NounA social, legal, or moral requirement, duty, contract, or promise that compels someone to follow or avoid a particular course of action."I feel I'm under obligation to attend my sister's wedding, even though we have a very frosty relationship."
3.NounA course of action imposed by society, law, or conscience by which someone is bound or restricted.
4.NounA legal agreement stipulating a specified action or forbearance by a party to the agreement; the document containing such agreement.
5.NounReason for being obliged to, that is, grateful for, something.