Indefatigable

Simple meaning

Indefatigable describes a person — or their energy — that never tires, never gives up, and keeps going no matter how much effort has already been spent.

Detailed meaning

Some people have a quality of endurance that goes beyond ordinary persistence. They do not just work hard — they seem genuinely incapable of being worn down. That quality is indefatigability, and the person who has it is indefatigable.

The word carries warmth and admiration. To call someone indefatigable is one of the highest compliments you can pay to a worker, a leader, a campaigner, or a caregiver. It says: I have watched you, and you have never stopped.

It often appears in formal writing, tributes, profiles, and recommendations — because it is a word that fits when ordinary praise is not quite enough. "She worked hard" does not capture what indefatigable captures. It says something specific: that fatigue itself seemed unable to touch this person.

Three areas where it lands perfectly:

• Professional tributes — honouring someone's career of sustained effort.
• Descriptions of activists or campaigners — people who persist against long odds.
• Profiles and recommendations — describing someone whose energy and commitment stand out as extraordinary.

Picture this

Think of a long-distance runner in the final kilometres of a marathon. Most runners are slowing, breathing heavily, heads lowered. But one runner maintains exactly the same form — upright, steady, unhurried — as if the miles behind her simply do not exist.

That runner has something the others are running out of. She is indefatigable. The distance has not diminished her.

Where to use it

Use indefatigable in writing and speech that calls for elevated, admiring language — tributes, formal recommendations, profiles, or any context where you want to convey deep respect for someone's endurance.

Where not to use it

Do not use indefatigable for someone who simply worked hard on one task or had a productive day. It describes a sustained, long-term quality of tirelessness — not a single impressive effort.

5 example sentences

1. The indefatigable volunteer had spent twenty years teaching literacy to adults every Saturday morning, without a single break.
2. His indefatigable spirit in the face of repeated setbacks inspired everyone who worked alongside him.
3. The journalist was indefatigable in her pursuit of the story — pursuing leads others had long abandoned.
4. What struck everyone about her leadership was her indefatigable energy: she seemed to get stronger as the crisis deepened.
5. An indefatigable curiosity is one of the greatest gifts a person can carry through life.

Common mistakes

Similar & opposite words

Similar (synonyms)

Opposite (antonyms)

Memory trick

A short story to remember it

At seventy-one, Mr. Krishnan still arrived at the community centre at seven each morning to prepare for the day's sessions. He had been doing it for thirty-four years.

People asked him often how he kept going — the funding cuts, the bureaucracy, the slow progress. He always looked puzzled by the question.

"I am not sure I understand tiredness in the way you mean it," he said once. "There is always someone who needs the next session."

A journalist writing about the centre called him indefatigable. He looked up the word and smiled quietly. He did not think he was exceptional. He thought he was simply someone who had not stopped.

Practice quiz

Summary

Indefatigable is reserved for people whose tirelessness becomes a defining quality — something admirable, almost hard to believe. It is the word for those who seem constitutionally incapable of giving up.