Synonyms and related words :
Byzantine, Herculean, abstruse, arduous, beyond one, brutal, burled, complex, complicated, crabbed, cramp, critical, daedal, delicate, demanding, difficile, difficult, effortful, elaborate, exacting, formidable, garbled, gnarled, gnarly, gordian, hairy, hard, hard to understand, hard-earned, hard-fought, intricate, involved, jawbreaking, jumbled, knobbed, knobbly, knobby, knoblike, knotted, knurled, knurly, laborious, labyrinthine, lumpy, mean, no picnic, nodal, noded, nodiform, nodose, nodular, nodulated, noduled, not easy, nubbled, nubbly, nubby, obfuscated, obscure, obscured, operose, overtechnical, perplexed, rigorous, rough, rugged, scrambled, set with thorns, severe, sophisticated, spiny, steep, sticky, strenuous, studded, terrible, thorny, ticklish, toilsome, torose, tough, tricky, tubercular, tuberculous, tuberose, tuberous, uphill, wicked