Duty
Etymology
From Anglo-French “duté,” from Old French “deu,” “owed,” from Latin “debere,” “to owe” — the same source as “debt” and “due.” A duty is, etymologically, what you owe; the moral weight of the word rests on the metaphor of an unpaid debt.
noun · /DOO-tee/
Something you are morally or legally bound to do because of your role, position, or the claims of others.
What it names
Reach for it to name a binding requirement to act — the flip side of someone else’s right or need.
Example
Jurors have a duty to weigh the evidence honestly, however tedious the trial.
Related idea
Duty and obligation overlap, but duty attaches to a standing role you occupy (a parent’s duty, a citizen’s duty), while obligation more often arises from a specific act or promise that binds you (the obligation created by signing a contract).
noun · /DOO-tee/
A tax charged on imported or certain goods.
What it names
a government levy on goods
Example
He paid customs duty on the wine; the airport shop is duty-free.
Related idea
Distinct from moral obligation, though both are things owed. Compare expense.