oner·​ous ˈä-nə-rəs How to pronounce onerous (audio) ˈō- How to pronounce onerous (audio)
: involving, imposing, or constituting a burden : troublesome
an onerous task
onerous regulations
an onerous mortgage
: having legal obligations that outweigh the advantages
an onerous contract
onerously adverb
onerousness noun

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What is the Difference Between onerous, burdensome, oppressive?

Not to go too heavy on the etymology, but the story behind onerous is at once straightforward and, dare we say, poetic. But perhaps that’s putting the cart before the horse. Onerous rolled into the English language during the 14th century, via Middle French, from the Latin adjective onerosus, "burdensome." That word, in turn, was hitched to the noun onus, meaning "burden" (source too of our word onus, which usually refers to a burden or responsibility). Onus shares an ancient root with the Sanskrit word anas, meaning "cart." So although onerous stresses a sense of laboriousness and often figurative heaviness (especially because something is distasteful, e.g. "the onerous task of cleaning up the mess"), it has a deep connection with a literal weight borne by a person, horse, or other beast of burden.

Choose the Right Synonym for onerous

onerous, burdensome, oppressive, exacting mean imposing hardship.

onerous stresses being laborious and heavy especially because distasteful.

the onerous task of cleaning up the mess

burdensome suggests causing mental as well as physical strain.

burdensome responsibilities

oppressive implies extreme harshness or severity in what is imposed.

the oppressive tyranny of a police state

exacting implies rigor or sternness rather than tyranny or injustice in the demands made or in the one demanding.

an exacting employer

Examples of onerous in a Sentence

Then everyone was asked, how fairly did you act?, from "extremely unfairly" (1) to "extremely fairly" (7). Next they watched someone else make the assignments, and judged that person's ethics. Selflessness was a virtual no-show: 87 out of 94 people opted for the easy task and gave the next guy the onerous one. Sharon Begley, Newsweek, 23 June 2008
The first hitch occurred when the state education department took a full six months after the new law was adopted to issue 12 pages of onerous rules and regulations governing Arkansas charter schools. Wendy Cole, Time, 10 June 2000
Environmentalism poses stark issues of survival, for humankind and for all those other tribes of creatures over which we have exercised our onerous dominion. Marilynne Robinson, The Death of Adam, 1998
Rap tested well, but early on the promoters said they wouldn't be booking any gangsta rap, a move at least partly designed to calm security concerns during the onerous process of complying with the strict mass-gathering laws enacted in the wake of the 1969 festival. John Milward, Rolling Stone, 11 Aug. 1994
The government imposed onerous taxes on imports. had the onerous and stressful job of notifying the families of soldiers killed in action See More
Recent Examples on the Web Someday, this reality may be modified by statute or judicial action, but until then, AI artwork may serve as an antidote to a copyright system that some see as onerous and overly restrictive. Benj Edwards, Ars Technica, 16 Nov. 2023 But such a requirement was seen as too onerous and expensive, so museums’ initial notices about objects sometimes mentioned only who had donated the item. Nicole Santa Cruz, ProPublica, 20 Oct. 2023 Pomerantz boasted that over a billion people have gone through the process Epic portrays as needlessly onerous to get apps outside the Play Store. Sean Hollister, The Verge, 7 Nov. 2023 While Americans can buy demilitarized fighter jets from the government, the permitting and approval process is onerous. Frank Witsil, Detroit Free Press, 14 Aug. 2023 Poilievre is also winning votes from legal Canadian immigrants by proposing occupational-licensing reforms that help such immigrants use skills previously honed in their home country that can’t be used in Canada because of onerous laws. Jon Hartley, National Review, 26 Oct. 2023 China has disbursed close to $1 trillion through the Belt and Road initiative, largely in loans, to build power plants, seaports, and other infrastructure across Asia, Africa and Latin America, but some countries are finding their debt obligations onerous. Tiffany May, New York Times, 18 Oct. 2023 Herbert Reul, also a Christian Democrat based in North Rhine-Westphalia, told the German network RND that the legislation would be overly onerous to enforce. Catie Edmondson,, 16 Aug. 2023 And Costco’s rules for redeeming rewards are more complicated and onerous than most other cards’. Aaron Hurd,, 18 Oct. 2023 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'onerous.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


Middle English, from Middle French honereus, from Latin onerosus, from oner-, onus burden; akin to Sanskrit anas cart

First Known Use

14th century, in the meaning defined at sense 1

Time Traveler
The first known use of onerous was in the 14th century


Dictionary Entries Near onerous

Cite this Entry

“Onerous.” Dictionary, Merriam-Webster, Accessed 28 Nov. 2023.

Kids Definition


: being difficult and unpleasant to do or to deal with
an onerous task
onerously adverb

Legal Definition


oner·​ous ˈä-nə-rəs, ˈō- How to pronounce onerous (audio)
: excessively burdensome or costly
: involving a return benefit, compensation, or consideration
an onerous donation
used chiefly in the civil law of Louisiana
see also onerous contract at contract compare gratuitous

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