[ahr-joo-uhs or, esp. British, ahr-dyoo-]
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  1. requiring great exertion; laborious; difficult: an arduous undertaking.
  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.

Origin of arduous

1530–40; < Latin arduus erect, steep, laborious; see -ous
Related formsar·du·ous·ly, adverbar·du·ous·ness, nounsu·per·ar·du·ous, adjectivesu·per·ar·du·ous·ly, adverbsu·per·ar·du·ous·ness, nounun·ar·du·ous, adjectiveun·ar·du·ous·ly, adverbun·ar·du·ous·ness, noun

Synonyms for arduous

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Antonyms for arduous

1. easy. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

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Contemporary Examples of arduous

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British Dictionary definitions for arduous


  1. requiring great physical or mental effort; difficult to accomplish; strenuous
  2. hard to endure; harsharduous conditions
  3. hard to overcome or surmount; steep or difficultan arduous track
Derived Formsarduously, adverbarduousness, noun

Word Origin for arduous

C16: from Latin arduus steep, difficult
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 arduous

1530s, "hard to accomplish, difficult to do," from Latin arduus "high, steep," also figuratively, "difficult," from PIE root *eredh- "to grow, high" (see ortho-). Literal sense of "high, steep, difficult to climb," attested in English from 1709.

Online Etymology Dictionary, © 2010 Douglas Harper