The phrase "relentless effort" means continuously working hard and not giving up, no matter how difficult the task or challenge may be. Full definition
All this is possible due to relentless effort of my parents - in - law, without them, it would have taken us a lot longer to get the house looking like home. (cookingninja.com)
It's been a hectic few weeks, with training, logistics management, sponsorship deals and crew planning requiring relentless effort. (blog.queensland.com)
Our efforts show that through activism and relentless efforts results can be achieved. (gaycitynews.nyc)