Synonyms and related words :
Herculean, abstruse, acanaceous, acanthoid, aciculate, aculeolate, arduous, barbed, barbellate, brambly, briery, bristly, brutal, complex, complicated, controversial, critical, delicate, demanding, difficile, difficult, exacting, formidable, hairy, hard, hard-earned, hard-fought, intricate, involved, jawbreaking, knotted, knotty, laborious, mean, muricate, nasty, nettlesome, no picnic, not easy, operose, painful, pricking, prickly, pricky, problematic, rigorous, rough, rugged, set with thorns, setaceous, setose, severe, spiculate, spiculose, spiked, spinous, spiny, steep, sticky, stinging, strenuous, tangled, thistly, ticklish, toilsome, tough, tricky, troublesome, uphill, vexatious, wicked, worrying