Someone who is indefatigable (adj.) can go on for a very long time without becoming tired. You might not be so happy to have an indefatigable guide on your walking trip––you'll have blisters, but she'll see no reason not to keep going.

  • Pronunciation: / ,ɪndɪ'fætɪɡəbl/
  • English description: showing sustained enthusiastic action with unflagging vitality
  • Synonyms: tireless
  • Chinese Translation:  不知疲倦的(bu4 zhi1 pi2 juan4 de)
  • Spanish Translation: infatigable
  • ORIGIN: Indefatigable comes from Latin indefatigabilis, formed from the prefixin- "not" plus defatigare "to tire out." Here the prefix de- means "entirely." You can remember the root fatigare because it sounds so much like the English fatigue.


  • The man was indefatigable in concert, a whirlwind who drilled his bands until they met his exacting standards.
  • The press follows every moment and the candidate himself seems indefatigable.

*New word description, story and part of "EXAMPLE SENTENCE" are cited in Vocabulary


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