Word of the day · 30 June 2026
indefatigable
/ˌɪndɪˈfætɪɡəbəl/
adjective
Persisting tirelessly; seemingly unable to be worn out.
In a sentence
- An indefatigable volunteer kept the food line moving all afternoon.
- Her indefatigable research turned up the missing citation.
- The campaign relied on an indefatigable field team.
In an image
Origin
From Latin indefatigabilis, from in- (not) and defatigare (to tire out), from fatigare (to weary).
History
English borrowed indefatigable for people and efforts that do not flag. It often praises organizers, athletes and advocates who return to the work daily. The long shape of the word matches the idea of endurance. Used carefully, it suggests stamina with purpose, not restless noise.
Nearby words
tireless · unflagging · persistent
Energy that keeps going after others stop.