indefatigable

in·de·fa·tig·a·ble
I1N1D2E1F4A1T1I1G2A1B3L1E1
UK/ˌɪn.dɪˈfæt.ɪ.ɡə.bəl/Australia, US/ˌɪn.dəˈfæt.ɪ.ɡə.bəl/Australia, US[ˌɪn.dəˈfæɾ.ɪ.ɡə.bəl]proscribed, sometimes/ˌɪn.dɪ.fəˈti.ɡə.bəl/

adjective

Extremely persistent and untiring.

Opposite
UncommonScrabble 20

Meanings

indefatigable1

adjectiveindefatigable (comparative more indefatigable, superlative most indefatigable)

comparative more indefatigable · superlative most indefatigable

  1. Extremely persistent and untiring.

    He was respected by all who knew him for his integrity and indefatigable attention to public business.

    1816 June – 1817 April/May (date written), [Mary Shelley], chapter I, in Frankenstein; or, The Modern Prometheus. […], volume I, London: […] [Macdonald and Son] for Lackington, Hughes, Harding, Mavor, & Jones, published 1 January 1818, →OCLC, page 39
    2 more examples

    [...] But he was at the ſame Time an excellent Scholar, and moſt indefatigable in teaching the two Lads.

    1749, Henry Fielding, “Containing Two Letters in Very Different Stiles”, in The History of Tom Jones, a Foundling, volume VI, London: A[ndrew] Millar, […], →OCLC, book XVIII, page 196

    All night long the Martians were hammering and stirring, sleepless, indefatigable, at work upon the machines they were making ready, and ever and again a puff of greenish-white smoke whirled up to the starlit sky.

    1895–1897, H[erbert] G[eorge] Wells, “Friday Night”, in The War of the Worlds, London: William Heinemann, published 1898, →OCLC, book I (The Coming of the Martians), pages 54–55

    Synonyms: inexhaustible, relentless, tireless, unflagging, unsinkable, untiring, unwearying · Antonyms: defatigable

Indefatigable2

proper noun
  1. Synonym of Santa Cruz, an island of Galapagos, Ecuador.

    Synonyms: Santa Cruz

Synonyms & antonyms

adjectiveExtremely persistent and untiring.

Opposite

proper nounSynonym of Santa Cruz, an island of Galapagos, Ecuador.

Similar

More synonyms by meaning

adjectiveshowing sustained enthusiastic action with unflagging vitality

Synonym sets from Open English WordNet, CC BY 4.0.

Origin

indefatigable · adjective

  1. Latinindēfatīgābilis“untiring”
  2. Englishindefatigable

From Middle French, from Latin indēfatīgābilis (“untiring”), from in- (“not”) + dēfatīgō (“to tire out”).

Full word history & related roots →

Indefatigable · proper noun

Named by the British Admiralty in honor of the HMS Indefatigable.

Full word history & related roots →

Translations

Ancient Greek ἀκάματος, ἄτρυτος
  • ἀκάματος (akámatos)extremely persistent and untiring
  • ἄτρυτος (átrutos)extremely persistent and untiring
Arabic لَا يَتْعَبُ
  • لَا يَتْعَبُ (lā yatʕabu)extremely persistent and untiring
Bulgarian неуморен
  • неуморен (neumoren)extremely persistent and untiring
Chinese Mandarin 不倦
  • 不倦 (bùjuàn)extremely persistent and untiring
Czech neúnavný
  • neúnavnýextremely persistent and untiring
Danish utrættelig
  • utrætteligextremely persistent and untiring
Dutch onvermoeibaar, onvermoeid
  • onvermoeibaarextremely persistent and untiring
  • onvermoeidextremely persistent and untiring
Finnish uupumaton, väsymätön
  • uupumatonextremely persistent and untiring
  • väsymätönextremely persistent and untiring
French infatigable
  • infatigableextremely persistent and untiring
German unermüdlich
  • unermüdlichextremely persistent and untiring
Greek ακούραστος
  • ακούραστος (akoúrastos)extremely persistent and untiring
Hebrew לא מתעיף
  • לא מתעיף (la' mth'if)extremely persistent and untiring
Hungarian fáradhatatlan, kitartó
  • fáradhatatlanextremely persistent and untiring
  • kitartóextremely persistent and untiring
Irish dochloíte, dosháraithe
  • dochloíteextremely persistent and untiring
  • dosháraitheextremely persistent and untiring
  • dothraochtaextremely persistent and untiring
  • dothuirsitheextremely persistent and untiring
Italian infaticabile
  • infaticabileextremely persistent and untiring
Māori pikoni
  • pikoniextremely persistent and untiring
Norwegian utrøttelig
  • utrøtteligextremely persistent and untiring
Portuguese infatigável
  • infatigávelextremely persistent and untiring
Russian неутоми́мый, неуста́нный
  • неутоми́мый (neutomímyj)extremely persistent and untiring
  • неуста́нный (neustánnyj)extremely persistent and untiring
  • упо́рный (upórnyj)extremely persistent and untiring
Scottish Gaelic do-shàrachaidh
  • do-shàrachaidhextremely persistent and untiring
Spanish incansable, infatigable
  • incansableextremely persistent and untiring
  • infatigableextremely persistent and untiring
Swedish outtröttlig
  • outtröttligextremely persistent and untiring
Ukrainian невто́мний, неосла́бний
  • невто́мний (nevtómnyj)extremely persistent and untiring
  • неосла́бний (neoslábnyj)extremely persistent and untiring
Welsh di-flino
  • di-flinoextremely persistent and untiring
Cite this entry
APA

indefatigable. (n.d.). In WatkinsX Dictionary. Retrieved November 3, 2026, from https://dictionary.watkinsx.com/word/indefatigable

MLA

“indefatigable.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/indefatigable. Accessed November 3, 2026.

Chicago

WatkinsX Dictionary, s.v. “indefatigable,” accessed November 3, 2026, https://dictionary.watkinsx.com/word/indefatigable.

Source: indefatigable on Wiktionary, CC BY-SA 4.0.