du·ty 
/ˈdu:ti, Brit ˈdju:ti/ noun
plural du·ties /ˈdu:ti, Brit ˈdju:ti/ noun 1 : something that is done as part of a job [count] ▪ His primary/main duty at the event is to take attendance. ▪ If new employees are unable to carry out their duties, they may be fired. ▪ She has a variety of adminsitrative duties. [noncount] ▪ Please report for duty [=show up for work] at 7 a.m. ▪ This year no firefighters/police were killed in the line of duty. [=while they were doing their jobs] ▪ In helping them, he went beyond the call of duty. [=did more than he was required or expected to do] synonyms 1task 2 : something that you must do because it is morally right or because the law requires it [count] ▪ We felt it was our duty to help. ▪ He has a duty to support his family. [noncount] ▪ They helped her out of a sense of duty. ▪ I'll be ready when duty calls. ▪ He was selected for jury duty. [=to serve on a jury] 3 [noncount] : active military service
▪ Her brother returned from duty overseas. ▪ a twelve-month tour of duty ▪ Many reserve troops were called into active duty. 4 : a tax on goods that are being brought into a country [count] ▪ All goods had a 15 percent (import) duty. ▪ customs duties [noncount] ▪ We had to pay duty on our souvenirs.
▪ Her brother returned from duty overseas. ▪ a twelve-month tour of duty ▪ Many reserve troops were called into active duty.
do duty as 1 : to do the work of (someone or something)
▪ He did (double) duty as the star and director of the film. 2 : to be used as (something)
▪ The backpack she uses at school also does duty as an overnight bag.
▪ He did (double) duty as the star and director of the film.
▪ The backpack she uses at school also does duty as an overnight bag.
off duty
: not working at a particular time
▪ I go off duty in two hours.
▪ I go off duty in two hours.
on duty
: working at a particular time
▪ I can't take any personal calls while I'm on duty.
▪ I can't take any personal calls while I'm on duty.
— see also heavy duty
