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

Derived Forms

• ˌindeˈfatigably, adverb
• ˌindeˌfatigaˈbility, noun

Other Words From

• inde·fati·ga·bili·ty inde·fati·ga·ble·ness noun
• inde·fati·ga·bly adverb

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

Unless you’re an indefatigable, insatiable scholar or fan, you wouldn’t want to read Highsmith’s diaries and notebooks in one sitting.

From Washington Blade

On the track, the indefatigable Czech was called the “Colossus,” set 17 world records up to 30K, and in the three-year build up to the Games he compiled a streak of 69 wins over 5,000m and 10,000m.

From Outside Online

As the indefatigable, utterly lovable Mal, Archie Renaux brings the heart.

From The Daily Beast

We’d also like to thank the indefatigable Jesse von Doom for helping us mind our schedules and keep our project running on time.

From ProPublica

Because the man is an indefatigable scholar of the game — he studies it as hard as maybe any quarterback but Tom Brady.

From Washington Post

“She would be my ‘boss lady,’” Crowe writes of the indefatigable Anne Marie.

From The Daily Beast

Perhaps even the indefatigable John Kerry might be discouraged from more futile and dispiriting peace talks.

From The Daily Beast

The exuberant, indefatigable Democrat from Oregon and the dour, taciturn Republican from New Hampshire made an odd couple.

From The Daily Beast

Richard Ben Cramer explores the abduction of Olympic athlete Kari Swenson and the indefatigable sheriff who hunted her abductor.

From The Daily Beast

Indefatigable in those two roles, he hankered after others, as well.

From The Daily Beast

His labors were indefatigable, and his works possess great merit.

From Project Gutenberg

There was a successful fishing that year, and Jacob Worse was indefatigable and in high spirits.

From Project Gutenberg

Nothing is more remarkable than the sustained application and indefatigable will which they bring to bear on their studies.

From Project Gutenberg

She heard unpleasant stories touching him through Sylvana, her nurse, an indefatigable gossip-monger.

From Project Gutenberg

The experiments which the indefatigable seeker had undertaken on atmospheric electricity interested her as much as they did him.

From Project Gutenberg

Related Words

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