[doo-tee, dyoo-]

noun, plural du·ties.


    do duty, to serve the same function; substitute for: bookcases that do duty as room dividers.
    off duty, not at one's post or work; at liberty: They spent their days off duty in hiking and fishing.
    on duty, at one's post or work; occupied; engaged: He was suspended from the force for being drunk while on duty.

Origin of duty

1250–1300; Middle English du(e)te < Anglo-French duete. See due, -ty2

Synonyms for duty

Synonym study

1. Duty, obligation refer to what one feels bound to do. Duty is what one performs, or avoids doing, in fulfillment of the permanent dictates of conscience, piety, right, or law: duty to one's country; one's duty to tell the truth, to raise children properly. An obligation is what one is bound to do to fulfill the dictates of usage, custom, or propriety, and to carry out a particular, specific, and often personal promise or agreement: financial obligations.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Related Words for on duty

busy, engaged, obliged, working, laboring

British Dictionary definitions for on duty


noun plural -ties

a task or action that a person is bound to perform for moral or legal reasons
respect or obedience due to a superior, older persons, etcfilial duty
the force that binds one morally or legally to one's obligations
a government tax, esp on imports
  1. the quantity or intensity of work for which a machine is designed
  2. a measure of the efficiency of a machine
the quantity of water necessary to irrigate an area of land to grow a particular crop
  1. a job or service allocated
  2. (as modifier)duty rota
do duty for to act as a substitute for
off duty not at work
on duty at work

Word Origin for duty

C13: from Anglo-French dueté, from Old French deu due
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for on duty



late 13c., from Anglo-French duete, from Old French deu "due, owed; proper, just," from Vulgar Latin *debutus, from Latin debitus, past participle of debere "to owe" (see debt). Related: Duties. The sense of "tax or fee on imports, exports, etc." is from late 15c.; duty-free as a noun is attested from 1958.

Online Etymology Dictionary, © 2010 Douglas Harper

on duty in Culture


A tax charged by a government, especially on an import.

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Idioms and Phrases with on duty

on duty

At one's post, at work, as in The new nurse was on duty that evening, or The watchman was fired because he was drunk on duty. [Mid-1600s] The antonym, off duty, means “not engaged in one's work,” as in Captain Smith was much more amiable when he was off duty. [Mid-1800s]


In addition to the idiom beginning with duty

  • duty bound

also see:

  • above and beyond (the call of duty)
  • active duty

do one's dutydouble dutyoff dutyon duty.

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.