indefatigable
adjective
in·de·fat·i·ga·ble ˌin-di-ˈfa-ti-gə-bəl 
: incapable of being fatigued : untiring
an indefatigable worker
indefatigability
ˌin-di-ˌfa-ti-gə-ˈbi-lə-tē
noun indefatigableness
ˌin-di-ˈfa-ti-gə-bəl-nəs
noun indefatigably
ˌin-di-ˈfa-ti-gə-blē
adverb 
Synonyms
- inexhaustible
- tireless
- unflagging
- untiring
- weariless
See all Synonyms & Antonyms 
Example Sentences
a person of indefatigable patience an indefatigable laborer who can work from sunrise to sunset
Recent Examples on the Web Lean and indefatigable, DeBakey often had three or four operations going at once. 
BostonGlobe.com, 30 Aug. 2022 The djinn has been romantically entangled with some of his summoners in the past, but despite the air of heartbreak, Elba plays his character as cheerfully indefatigable. David Sims, The Atlantic, 27 Aug. 2022 Such an exaggerated approach is perhaps better suited to skits, but Balan compensates with indefatigable musical showmanship. Los Angeles Times, 12 Aug. 2022 Casey introduced a video that featured high praise for Jeffrey’s indefatigable work from George Clooney, Hugh Jackman, Catherine Zeta-Jones and Michael Douglas. Chris Gardner, The Hollywood Reporter, 20 June 2022 Of course, that success was due in large part to the indefatigable Schumacher. Robert Ross, Robb Report, 1 Aug. 2022 Palmer improvised that line, showcasing her effortless creativity and indefatigable hustle. New York Times, 22 July 2022 The married artists Michelle Grabner and Brad Killam are apparently indefatigable. New York Times, 6 July 2022 An indefatigable evil has placed some of our favorite Stranger Things characters to love (and hate) in eternal sleep. Keith Nelson, Men's Health, 5 July 2022 See More
BostonGlobe.com, 30 Aug. 2022 The djinn has been romantically entangled with some of his summoners in the past, but despite the air of heartbreak, Elba plays his character as cheerfully indefatigable. David Sims, The Atlantic, 27 Aug. 2022 Such an exaggerated approach is perhaps better suited to skits, but Balan compensates with indefatigable musical showmanship. Los Angeles Times, 12 Aug. 2022 Casey introduced a video that featured high praise for Jeffrey’s indefatigable work from George Clooney, Hugh Jackman, Catherine Zeta-Jones and Michael Douglas. Chris Gardner, The Hollywood Reporter, 20 June 2022 Of course, that success was due in large part to the indefatigable Schumacher. Robert Ross, Robb Report, 1 Aug. 2022 Palmer improvised that line, showcasing her effortless creativity and indefatigable hustle. New York Times, 22 July 2022 The married artists Michelle Grabner and Brad Killam are apparently indefatigable. New York Times, 6 July 2022 An indefatigable evil has placed some of our favorite Stranger Things characters to love (and hate) in eternal sleep. Keith Nelson, Men's Health, 5 July 2022 See More Word History
Etymology
Middle French, from Latin indefatigabilis, from in- + defatigare to fatigue, from de- + fatigare to fatigue
First Known Use
1608, in the meaning defined above
indefatigable
adjective
as in tireless
showing no signs of weariness even after long hard effort an indefatigable laborer who can work from sunrise to sunset Synonyms & Similar Words
Relevance
- tireless
- meticulous
- untiring
- relentless
- unflagging
- conscientious
- inexhaustible
- vigorous
- diligent
- active
- energetic
- intense
- steadfast
- assiduous
- persistent
- tenacious
- spirited
- determined
- sedulous
- unrelenting
- painstaking
- unwavering
- unremitting
- dogged
- busy
- unfailing
- steady
- unfaltering
- stubborn
- unflinching
- persevering
- industrious
- pertinacious
- patient
- weariless
- unabated
- dynamic
- plodding
- feverish
- hard
- strenuous
- laborious
- slavish
Antonyms & Near Antonyms
- sluggish
- indolent
- lackadaisical
- lazy
- slothful
- listless
- shiftless
- laggard
- desultory
- casual
- spiritless
- languid
- apathetic
- overworked
- beat
- broken
- drained
- sapped
- overtaxed
- jaded
- enervated
- wearied
- spent
- burnt-out
- worn-out
- burned-out
- played out
- tuckered (out)
- done in