bounden duty
old-fashioned Some duty or task one feels obligated to perform or undertake. She considered it her bounden duty to expose the corruption in her company. The president said in his address that the country has a bounden duty to help other nations in need.
a bounden duty
a responsibility regarded by yourself or others as obligatory. Bounden as the past participle of bind is now archaic in all contexts and is seldom found except in this phrase.
bounden duty
A firm obligation. The adjective bounden, which survives only in this cliché, means being indebted to someone. The term dates from the early 1500s and appears in the Book of Common Prayer: “We beseech Thee to accept this our bounden duty and service.” See also duty bound.