- The definition of indefatigable is a person or something that has tireless persistence.
Someone who keeps trying and trying to learn a skill and who never gives up is an example of a person who would be described as indefatigable.
Origin: MFr indéfatigable from Classical Latin indefatigabilis from in-, not plush defatigare, to tire out, weary: see de- and amp; fatigue
Used by arrangement with John Wiley & Sons, Inc.
Origin: Obsolete French indéfatigable, from Latin indēfatīgābilis : in-, not; see in-1 + dēfatīgāre, to tire out (dē-, intensive pref.; see de- + fatīgāre, to weary).
- inˌde·fatˌi·ga·bilˈi·ty, inˌde·fatˈi·ga·ble·ness noun
- inˌde·fatˈi·ga·bly adverb