Definition of herculean:
superhuman, muscular, gargantuan, monster, complicated, compact, behemoth, massy, mammoth, beefy, mountainous, tremendous, prodigious, hard, knock-down, sinewy, big, gigantesque, demanding, taxing, huge, be an effort, barrel-chested, tough, pythonic, Brobdingnagian, enormous, Bunyanesque, large, massive, full, potent, walloping, heroic, mastodonic, Cyclopean, punishing, elephantine, heavy, monstrous, strenuous, jumbo, burly, powerful, coltish, titanic, brawny, giant, challenging, stupendous, bullnecked, vast, built, difficult, gigantic, whopping, colossal, monumental, arduous, mighty, hefty, immense.
The men were smaller, their breasts being exceedingly broad, their heads immensely big, their limbs developed, their strength herculean; their shape was not so handsome as that of the savages I had just left; their colour of a dark bronze, very dark indeed; their noses are less aquiline, their eyes yellow and fully open- a la Chinoise.- "Adventures in the Philippine Islands", Paul P. de La Gironière.
If I had been there, I would have saved Orlando at the cost of- He was interrupted at this point by the repetition of the cry which had before reached him in the cabin; but how much more awful did that despairing cry sound near at hand, as it issued full, deep- toned, and strong, from the chest of the Herculean man!- "The Madman and the Pirate", R.M. Ballantyne.
The cool ocean refreshed him almost as much as would a draft of water, so that it was with renewed vigor that he brought the smaller boat alongside the derelict, and, after many herculean efforts, succeeded in dragging it onto the slimy ship's bottom.- "The Return of Tarzan", Edgar Rice Burroughs.