Herculean abstruse arduous backbreaking brutal burdensome complex critical crushing delicate demanding difficile difficult effortful exacting forced formidable grueling hairy hard hard-fought heavy hefty intricate jawbreaking killing knotted knotty labored laborious mean no picnic not easy onerous operose oppressive painful punishing rigorous rough rugged set with thorns severe spiny steep strained strenuous thorny ticklish toilsome tough tricky troublesome uphill wearisome wicked