indefatigable
Translation
tireless, unwearying, persistent
Examples
She was an indefatigable campaigner for human rights.
She was a tireless campaigner for human rights.
Grammar Patterns
indefatigable ((noun)) He is an indefatigable worker.
Similar Words
Synonyms: tireless, unwearying, persistent; Antonyms: weary, lethargic
Etymology
From Latin 'in-' (not) + 'de-' (down, completely) + 'fatigare' (to tire). Literally means 'not able to be tired out'.
Memory Tips
Think of someone who cannot be defeated by fatigue. The 'in-' prefix means 'not', and 'fatigue' means tiredness.