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arduous

American  
[ahr-joo-uhs, ahr-dyoo-] / ˈɑr dʒu əs, ˈɑr dyu- /

adjective

  1. requiring great exertion; laborious; difficult.

    an arduous undertaking.

    Synonyms:
    exhausting, burdensome, wearisome, onerous, toilsome, hard
    Antonyms:
    easy
  2. requiring or using much energy and vigor; strenuous.

    making an arduous effort.

  3. hard to climb; steep.

    an arduous path up the hill.

  4. hard to endure; full of hardships; severe.

    an arduous winter.


arduous British  
/ ˈɑːdjʊəs /

adjective

  1. requiring great physical or mental effort; difficult to accomplish; strenuous

  2. hard to endure; harsh

    arduous conditions

  3. hard to overcome or surmount; steep or difficult

    an arduous track

"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

Other Word Forms

Etymology

Origin of arduous

First recorded in 1530–40; from Latin arduus “erect, laborious, steep”

Explanation

Use the adjective arduous to describe an activity that takes a lot of effort. Writing all those college essays and filling out the applications is an arduous process! Arduous was first used in English to mean "steep" or "difficult to climb." If you're an outdoorsman, hiking up a mountain is a lot of fun, but if you're a couch potato, it's an arduous trek. Today, the word can be used figuratively for something that is difficult or takes a lot of work. If you spend an arduous week studying for your final exams, you'll do well because you've worked really hard!

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Vocabulary lists containing arduous

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

He agrees that tech should help to “relieve humans of arduous, repetitive or dangerous tasks” and “provide intelligent support,” but also warns of growing A.I.-induced inequality, which exacerbates poverty and forced migration.

From Slate • May 28, 2026

After facing Crystal Palace in Krakow, Poland, in the first leg of their Uefa Conference League semi-final on Thursday, the Ukrainian Premier League leaders will begin an arduous journey.

From BBC • Apr. 30, 2026

There was no shortage of ideas for other ways to ease the financial burdens facing Californians, but few specifics on how they would deliver on those promises given the state’s complex and arduous legislative process.

From Los Angeles Times • Apr. 29, 2026

Even as Gulf tanker traffic slowly resumes, the road back to normal food production will be long and arduous, given the war's impact on fertiliser supplies, the UN has warned.

From Barron's • Apr. 10, 2026

Openly, Bobby disparaged how he’d performed, but the Soviet chess establishment was dazzled by how he managed to place so high under such arduous conditions.

From "Endgame" by Frank Brady

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