duty

noun7

1. •
   something that the law or a sense of right and wrong says a person must do

   • Do your duty by me! -No, we don't have a duty to keep you abreast.
2. •
   The state of being at work and responsible for or doing a particular task.

   • I’m on duty from 6 pm to 6 am.
3. •
   An excise tax; especially, one on imports or exports.
4. •
   (euphemistic) The act of urination or defecation, especially for a dog.

   • The basic idea in housebreaking is not to wait until the puppy sins and then punish him; it is to call nature to your aid and thus make it easy for him to do his duty. — 1927
5. •
   The efficiency of an engine in work done per unit of fuel; particularly, the number of pounds of water which a steam pumping engine can raise one foot by burning one bushel or hundredweight of coal.
6. •
   (no longer used) Respect; reverence; regard; act of respect; homage.

   • It [the letter] was written with a plain, unaffected, homely piety that I knew to be genuine, and ended with ‘my duty to my ever darling’—meaning myself. — 1849
7. •
   (no longer used) One's due, something one is owed; a debt or fee.

   • Take that which is thy duty, and goo thy waye. — 1526