operose Synonyms

heavy laborious toilsome gruelling punishing hard backbreaking grueling arduous tricky thorny taxing strenuous sticky severe serious rugged toilful labour-consuming labor-intensive labour-intensive time-consuming weighty uphill not easy labor-consuming tough trying rough problematic ambitious grinding grievous grave elaborate difficult difficile complicated complex hefty industrious intricate ponderous painful oppressive onerous nasty leaden knotty knotted