D defs.my
Entry 7 senses Webster, 1913

Duty

/dyōōtē/ · Du·ty · IPA /ˈdjuː.ti/
01 n. That which is due; payment.
pl. Duties ((#))
  1. 1.
    That which is due; payment.[Obs. as signifying a material thing.]
    “When thou receivest money for thy labor or ware, thou receivest thy duty.” — Tyndale.
  2. 2.
    That which a person is bound by moral obligation to do, or refrain from doing; that which one ought to do; service morally obligatory.
    “Forgetting his duty toward God, his sovereign lord, and his country.” Hallam.
  3. 3.
    Hence, any assigned service or business; as, the duties of a policeman, or a soldier; to be on duty.
    “With records sweet of duties done.” Keble.
    “To employ him on the hardest and most imperative duty.” Hallam.
    Duty is a graver term than obligation. A duty hardly exists to do trivial things; but there may be an obligation to do them.” — C. J. Smith.
  4. 4.
    Specifically, obedience or submission due to parents and superiors.
  5. 5.
    Respect; reverence; regard; act of respect; homage.
  6. 6.
    The efficiency of an engine, especially a steam pumping engine, as measured by work done by a certain quantity of fuel; usually, the number of pounds of water lifted one foot by one bushel of coal (94 lbs. old standard), or by 1 cwt. (112 lbs., England, or 100 lbs., United States).(Engin.)
  7. 7.
    Tax, toll, impost, or customs; excise; any sum of money required by government to be paid on the importation, exportation, or consumption of goods.(Com.)
Phrases & compounds
Ad valorem duty — a duty which is graded according to the cost, or market value, of the article taxed. See Ad valorem.
Specific duty — a duty of a specific sum assessed on an article without reference to its value or market.
On duty — actually engaged in the performance of one's assigned task.