Definition of "indefatigable"
indefatigable
adjective
comparative more indefatigable, superlative most indefatigable
Extremely persistent and untiring.
Quotations
Whoever hath an Ambition to be heard in a Crowd, muſt preſs, and ſqueeze, and thruſt, and climb with indefatigable Pains, till he has exalted himſelf to a certain Degree of Altitude above them.
1704, [Jonathan Swift], “Section I. The Introduction.”, in A Tale of a Tub. […], London: […] John Nutt, […], page 33
All night long the Martians were hammering and stirring, sleepless, indefatigable, at work upon the machines they were making ready, and ever and again a puff of greenish-white smoke whirled up to the starlit sky.
1895–1897, H[erbert] G[eorge] Wells, “Friday Night”, in The War of the Worlds, London: William Heinemann, published 1898, book I (The Coming of the Martians), pages 54–55