1) Arduous 2) Backbreaking 3) Challenging 4) Claiming 5) Difficult 6) Exacting 7) Exhausting 8) Exigent 9) Hard 10) Hard to please 11) Harsh 12) Not easy 13) Punishing 14) Requiring much effort 15) Rigorous 16) Rough 17) Severe 18) Stern 19) Strict 20) Stringent 21) Taxing 22) Testing 23) Thorough 24) Tight 1) Arduous 2) Bossy 3) Concentrated 4) Difficult 5) Exhausting 6) Gruelling 7) Hard 8) Insistent 9) Particular 10) Persistent 11) Severe 12) Stern 13) Strict 14) Stringent 15) Tiring 
• (p. pr. & vb. n.) of Demand
[adj] - requiring more than usually expected or thought due
requiring or claiming more than is generally felt by others to be due: a demanding teacher. · calling for intensive effort or attention; taxing: a demanding job.