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

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

Peters continued to tour and release music during a three-decade battle with several forms of cancer, putting himself up as an indefatigable advocate for blood cancer patients. —Gil Kaufman, Billboard, 29 Apr. 2025

Below is an itinerary custom-built for those with an indefatigable indie spirit. —Brad Japhe, Forbes.com, 30 Apr. 2025

My childhood idol, and the indefatigable chronicler of our games (check Partletonsports.com). —Nick Canepa, San Diego Union-Tribune, 19 Apr. 2025

Even the indefatigable Benton slowed down in her later years, afflicted with a heart condition. —Richard Selcer, Fort Worth Star-Telegram, 12 Apr. 2025

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

Kids Definition

indefatigable

adjective

in·​de·​fat·​i·​ga·​ble ˌin-di-ˈfat-i-gə-bəl 

: capable of working a long time without tiring : tireless

an indefatigable teacher

indefatigably

-blē 

adverb