1. Duty, obligation refer to what one feels bound to do. Duty is what one performs, or avoids doing, in fulfillment of the permanent dictates of conscience, piety, right, or law: duty to one's country; one's duty to tell the truth, to raise children properly. An obligation is what one is bound to do to fulfill the dictates of usage, custom, or propriety, and to carry out a particular, specific, and often personal promise or agreement: financial obligations. 3. responsibility, business. 4. deference.