indefatigable

/ˌɪndɪˈfætɪɡəbəl/
adjective
  1. Never becoming tired or giving up; extremely persistent and energetic.
    • The indefatigable worker kept going even after 12 hours on the job.
    • She was an indefatigable advocate for animal rights, speaking at every event she could.
    • His indefatigable spirit inspired the whole team to keep trying.
Antonyms
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