indefatigable
adjective/ˌɪndɪˈfætɪɡəbl/
/ˌɪndɪˈfætɪɡəbl/
(formal, approving)- never giving up or getting tired of doing something
- an indefatigable defender of human rights
- She was indefatigable in her search for the truth.
Word Originearly 17th cent.: from French, or from Latin indefatigabilis, from in- ‘not’ + de- ‘away, completely’ + fatigare ‘wear out’.
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indefatigable