indefatigable

[in-di-fat-i-guh-buhl]

adjective

1. incapable of being tired out; not yielding to fatigue; untiring.

   Synonyms: persevering, inexhaustible, tireless

indefatigable

/ ˌɪndɪˈfætɪɡəbəl /

adjective

1. unable to be tired out; unflagging

Other Word Forms

• indefatigably adverb
• indefatigability noun
• indefatigableness noun

Word History and Origins

Origin of indefatigable¹

1580–90; < Latin indēfatīgābilis untiring, equivalent to in- in- ³ + dēfatīgā ( re ) to tire out ( de-, fatigue ) + -bilis -ble

Word History and Origins

Origin of indefatigable¹

C16: from Latin indēfatīgābilis, from _in- ¹ + dēfatīgāre, from fatīgāre to tire

Example Sentences

Xenarios, who died of cancer on Sept. 6 at home in New York at age 79, was the indefatigable soul of the organization, leading it for 40 years until her retirement in 2017.

Read more on The Wall Street Journal

But she is also indefatigable: She believes that she must win to save democracy, yet she seems to shoulder that formidable burden without breaking a sweat.

Read more on Los Angeles Times

Tony Doherty, chair of the Bloody Sunday Trust, said: "This day is a tribute to the strength of the families, whose indefatigable campaign for justice has made this happen."

Read more on BBC

It also said he was "indefatigable to the end" and "driven by relentless curiosity and a deep attention to the present and to people".

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Being part of the show "wasn't even on my bucket list of dreams," she adds, "because it was an indefatigable dream to even consider because it was impossible."

Read more on BBC

Related Words

• assiduous 
• diligent 
• dogged 
• energetic 
• inexhaustible 
• painstaking 
• relentless 
• tireless 
• unflagging 
• unwavering 
• vigorous