Indefatigable means never seeming to tire. An indefatigable campaigner, indefatigable energy, indefatigable in her work.
It is always admiring and belongs to campaigners and researchers, where the point is years of effort rather than one great push. The Latin means not able to be tired out.
1adjectiveindefatigableNever seeming to tire.
“The indefatigable nurse worked double shifts all winter without a single complaint.”
indefatigable is a quality.
Latin indefatigabilis is in-, not, plus defatigare, to tire out.
Latin
indēfatīgābilis — untiring
English, today
indefatigable
Built from
From Middle French -, from Latin indēfatīgābilis (“untiring”), from in- (“not”) + dēfatīgō (“to tire out”).
Etymology from Wiktionary, CC BY-SA