The phrase "herculean effort" means putting in an incredibly strong and determined amount of work, similar to the legendary strength and effort of the mythical hero Hercules. Full definition
After 48 hours of Herculean effort by Vernon, we got the facts. (labour-uncut.co.uk)
«Substantial reductions in emissions are possible for both the U.S. and the rest of the world, but it will take herculean efforts and transforming the global energy system into one that does not use the sky as a waste dump,» Caldeira said. (wxshift.com)
Ernst came from behind and surged in recent weeks despite herculean efforts by powerful Democratic figures to save Braley, including a campaign visit by Obama's wife, Michelle. (entrepreneur.com)