Synonyms and related words :
Herculean, Spartan, Spartanic, abstruse, accurate, arduous, astringent, attentive, austere, authoritarian, brutal, burdensome, cajoling, clamant, clamorous, close, coaxing, complex, conscientious, correct, critical, crying, delicate, detailed, difficile, difficult, dour, draining, dunning, exact, exacting, exigent, exorbitant, exquisite, extortionate, fine, finical, finicking, finicky, formidable, fussy, grasping, grievous, grim, hairy, hard, hard-earned, hard-fought, harsh, imperative, importunate, insistent, instant, intricate, jawbreaking, knotted, knotty, laborious, loud, mean, meticulous, minute, nagging, narrow, nice, no picnic, not easy, operose, oppressive, particular, persistent, pertinacious, pestering, plaguing, precise, precisianistic, precisionistic, pressing, punctilious, punctual, refined, religious, rigid, rigorous, rough, rugged, scrupulous, scrutinizing, set with thorns, severe, spiny, steep, stern, strenuous, strict, stringent, subtle, taxing, teasing, thorny, ticklish, toilsome, tough, tricky, trying, unsparing, uphill, urgent, weighty, wheedling, wicked