indefatigable

[in-di-fat-i-guh-buhl] / ˌɪn dɪˈfæt ɪ gə bəl /

ADJECTIVE

untiring

Synonyms

STRONGEST

assiduous diligent dogged energetic inexhaustible painstaking relentless tireless unflagging unwavering vigorous

WEAK

active bound and determined dead set on determined hell-bent industrious ironclad nose to grindstone patient persevering persistent pertinacious sedulous steadfast stop-at-nothing strenuous unfaltering unflinching unremitting unwearied unwearying

Antonyms

STRONGEST

changing idle inactive indifferent lazy lethargic negligent tired wavering

WEAK

fatigued weary

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

At first, Epstein, an indefatigable social networker, was anxious over whether Tisch liked him or not.

From The Wall Street Journal • Feb. 12, 2026

But an indefatigable Volkanovski's agility and relentless striking eventually wore down his flagging challenger, who was unable to land a knockout in the final round.

From Barron's • Feb. 1, 2026

The thrill of seeing a fearless, indefatigable performer single-handedly populate the stage with the myriad figures of this masterwork never lets up.

From Los Angeles Times • Jan. 25, 2026

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

From BBC • Sep. 4, 2025

A more resolute, indefatigable pioneer never wrought amidst rocks and dangers.

From "Jane Eyre" by Charlotte Brontë

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