What is Primary Obligation?

Legal Definition
An obligation which is the principal object of the contract. For example, the primary obligation of the seller is to deliver the thing sold, and to transfer the title to it. It is distinguished from the accessory or secondary obligation to pay damages for not doing so. 1 Bouv. Inst. no. 702. The words "primary" and "direct," contrasted with "secondary," when spoken with reference to an obligation, refer to the remedy provided by law for enforcing the obligation, rather than to the character and limits of the obligation itself. Kilton v. Providence Tool Co.., 22 R. I. 605, 48 Atl. lo39.
-- Black's Law Dictionary
Legal Definition
One imposed by law by one’s voluntary undertaking, or by the law on the grounds of public policy ot utility, e. g., to perform one’s contract, to refrain from trespass. See Secondary obligation. See, also, 8 Harv. Law Rev. 200.
-- Ballentine's Law Dictionary