Herculean abstruse adverse antagonistic arduous brutal complex conflicting contrary counter counteractive critical delicate demanding detrimental difficile difficult exacting formidable hairy hard hard-earned hard-fought harmful hostile in opposition inimical intricate jawbreaking knotted knotty laborious mean miserable no picnic operose opposed opposing opposite rigorous rough rugged set with thorns severe sinister spiny steep strenuous stressful thorny ticklish toilsome tough tricky troublesome troublous trying unfavorable untoward uphill wicked wretched