duty in WordNet English dictionary

1. the social force that binds you to the courses of action demanded by that force
   "we must instill a sense of duty in our children"; "every right implies a responsibility; every opportunity, an obligation; every possession, a duty"- John D.Rockefeller Jr
   duty  responsibility  obligation 
   
2. work that you are obliged to perform for moral or legal reasons
   "the duties of the job"
   duty 
   
3. a government tax on imports or exports
   "they signed a treaty to lower duties on trade between their countries"
   duty  tariff