'On duty' definitions:

Definition of 'On duty'

From: GCIDE
  • Duty \Du"ty\, n.; pl. Duties. [From Due.]
  • 1. That which is due; payment. [Obs. as signifying a material thing.] [1913 Webster]
  • When thou receivest money for thy labor or ware, thou receivest thy duty. --Tyndale. [1913 Webster]
  • 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. [1913 Webster]
  • Forgetting his duty toward God, his sovereign lord, and his country. --Hallam. [1913 Webster]
  • 3. Hence, any assigned service or business; as, the duties of a policeman, or a soldier; to be on duty. [1913 Webster]
  • With records sweet of duties done. --Keble. [1913 Webster]
  • To employ him on the hardest and most imperative duty. --Hallam. [1913 Webster]
  • 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. [1913 Webster]
  • 4. Specifically, obedience or submission due to parents and superiors. --Shak. [1913 Webster]
  • 5. Respect; reverence; regard; act of respect; homage. "My duty to you." --Shak. [1913 Webster]
  • 6. (Engin.) 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). [1913 Webster]
  • 7. (Com.) Tax, toll, impost, or customs; excise; any sum of money required by government to be paid on the importation, exportation, or consumption of goods. [1913 Webster]
  • Note: An impost on land or other real estate, and on the stock of farmers, is not called a duty, but a direct tax. [U.S.] [1913 Webster]
  • 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. [1913 Webster]

Synonyms of 'on duty'

From: Moby Thesaurus