Synonyms and related words :
Herculean, abstruse, adverse, antagonistic, arduous, awkward, baffling, beyond one, bloody-minded, brutal, burdensome, cantankerous, complex, complicated, conflicting, contrary, counter, counteractive, crabbed, cramp, critical, cross-grained, dark, delicate, demanding, detrimental, difficile, effortful, enigmatical, exacting, fastidious, finical, finicking, finicky, finikin, formidable, froward, fuss-budgety, fussy, garbled, grim, hairy, hard, hard to please, hard to understand, hard-earned, hard-fought, harmful, hostile, ill-behaved, in opposition, inimical, intractable, intricate, irascible, jawbreaking, jumbled, knotted, knotty, labored, laborious, mean, miserable, naughty, nit-picking, no picnic, not easy, obfuscated, obscure, obscured, obstinate, obstructive, onerous, operose, opposed, opposing, opposite, ornery, overtechnical, particular, pawky, pernickety, perplexed, perplexing, persnickety, perverse, problem, problematic, problematical, profound, puzzling, queasy, recalcitrant, recondite, refractory, rigorous, rough, rugged, scabrous, scrambled, sensitive, set with thorns, severe, sinister, spiny, squeamish, steep, strenuous, stressful, stubborn, stuffy, sulky, sullen, thorny, ticklish, toilsome, tough, tricky, troubled, troublesome, troubling, troublous, trying, unaccommodating, uncompromising, unfavorable, unmanageable, untoward, unyielding, uphill, wayward, wicked, wretched, wrongheaded