: working very hard with a lot of energy for a long time : never seeming to get tired
the rescuers' untiring efforts
She is an untiring [=tireless] advocate for the poor.
Cite this Entry
“Untiring.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/untiring. Accessed 23 Jun. 2026.
Copy Citation
