grueling

• POS: Adjective, Noun
• HYPHEN: gru=el=ing

CIDE DICTIONARY

grueling, adj. 

 characterized by toilsome effort; requiring extreme physical or mental effort; as, a grueling campaign.  [WordNet 1.5]

THESAURUS

grueling

Herculean, annoying, arduous, backbreaking, besetting, bothersome, burdensome, castigatory, chastening, chastising, corrective, crushing, devitalizing, disciplinary, draining, effortful, enervating, enfeebling, exhausting, fatiguesome, fatiguing, forced, hard-earned, hard-fought, heavy, hefty, inflictive, irksome, killing, labored, laborious, onerous, operose, oppressive, painful, penal, penological, plaguey, punishing, punitive, punitory, retributive, sapping, strained, straining, strenuous, stressful, tiresome, tiring, toilsome, tough, troublesome, trying, uphill, vexatious, weakening, weariful, wearing, wearisome, wearying