Indefatigable and defatigable

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Indefatigable is a word that is often found confusing, as well as its rarely-used antonym, defatigable. Antonyms are two or more words that have opposite meanings. We will examine the definitions of indefatigable and defatigable, where these terms came from and some examples of their use in sentences.

Indefatigable describes someone who is untiring, someone energetic and relentless. Someone who is indefatigable can not be deterred. Indefatigable is an adjective, related words are indefatigability, indefatigably. The word indefatigable is derived from the Latin word indefatigabilis, meaning can not be tired out.

Defatigable means easily tired out, someone listless and unenergetic. Defatigable is a synonym of fatigable, which at first seems counter-intuitive. The meaning hinges on the prefix de-, which is usually used to coin a word that means the opposite action, such as bug and debug, or forest and deforest. However, the prefix de- may also mean thoroughly, or down to the bottom of something. In this case, defatigable means to thoroughly fatigue someone. the word defatigable is rarely used today, except as a play on words.


Having missed Mayo’s league campaign earlier in the year, taking five months off to do some travelling, she reckons she was only reaching peak fitness towards the end of Carnacon’s Championship run, which might account for her indefatigable performances in midfield. (The Irish Times)

“He is an indefatigable fighter for democratic change in Zimbabwe and his leadership and guidance continues to make the party stronger and stronger.” (The Zimbabwe Mail)

Orton’s underrated ring generalship could be the tracks the runaway freight train Wyatt needs, and Wyatt’s just the kind of electric presence to keep the defatigable eyes of Orton’s audience peeled. (The Auburn Citizen)