in·​de·​fat·​i·​ga·​ble ˌin-di-ˈfa-ti-gə-bəl How to pronounce indefatigable (audio)
: incapable of being fatigued : untiring
an indefatigable worker
indefatigability noun
indefatigableness noun
indefatigably adverb

Examples of indefatigable in a Sentence

a person of indefatigable patience an indefatigable laborer who can work from sunrise to sunset
Recent Examples on the Web Cruz, Carlson, and the indefatigable MTG et alia don’t want to be included. Ana Marie Cox, The New Republic, 14 Sep. 2023 When Gauff broke Sabalenka to open the third set—with an overhead smash after yet another indefatigable defensive stand—the crowd reached a state of delirium that tennis produces only in the cavernous Ashe Stadium, and only for an American on the verge of a U.S. Open championship. Gerald Marzorati, The New Yorker, 10 Sep. 2023 Whether writing best-selling books, speaking at Occupy Wall Street, being arrested at an anti-pipeline protest or campaigning for Bernie Sanders, Klein has remained indefatigable and on message. Jennifer Szalai, New York Times, 30 Aug. 2023 For that reason, Votto predicts a return of the pesky, indefatigable contact hitter. Zach Buchanan, New York Times, 28 July 2023 New salary rules may jeopardize the industry June 1, 2023 On this sunny day, however, the goats are streaming down the hill to a new grazing area, egged on by the indefatigable herding dog Bernie. Jeanette Marantos, Los Angeles Times, 26 June 2023 Christian Petersen/Getty ▪ Good job, Wimbledon, in extending a wild card invite to the indefatigable Venus Williams. Tara Sullivan,, 26 June 2023 Maya’s Carl is ever the goading, jousting counterpoint, play-acting and indefatigable for Jody’s benefit. David L. Coddon, San Diego Union-Tribune, 24 June 2023 The rest of Denver’s indefatigable eight-man rotation bolstered the team’s two biggest stars until the end. Tania Ganguli, New York Times, 12 June 2023 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'indefatigable.' 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 French, from Latin indefatigabilis, from in- + defatigare to fatigue, from de- + fatigare to fatigue

First Known Use

1608, in the meaning defined above

Time Traveler
The first known use of indefatigable was in 1608

Dictionary Entries Near indefatigable

Cite this Entry

“Indefatigable.” Dictionary, Merriam-Webster, Accessed 28 Sep. 2023.

Kids Definition


in·​de·​fat·​i·​ga·​ble ˌin-di-ˈfat-i-gə-bəl How to pronounce indefatigable (audio)
: capable of working a long time without tiring : tireless
an indefatigable teacher
indefatigably adverb

More from Merriam-Webster on indefatigable

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