demanding (adj.)

• abstruse
• accurate
• arduous
• astringent
• attentive
• austere
• authoritarian
• brutal
• burdensome
• clamant
• clamorous
• close
• coaxing
• complex
• conscientious
• correct
• critical
• crying
• delicate
• detailed
• difficult
• dour
• draining
• exact
• exacting
• exigent
• exorbitant
• exquisite
• extortionate
• fine
• finical
• finicky
• formidable
• fussy
• grasping
• grievous
• grim
• hairy
• hard
• hard-fought
• harsh
• imperative
• importunate
• insistent
• instant
• intricate
• knotted
• knotty
• laborious
• loud
• mean
• meticulous
• minute
• nagging
• narrow
• nice
• operose
• oppressive
• particular
• persistent
• pertinacious
• pestering
• precise
• pressing
• punctilious
• punctual
• refined
• religious
• rigid
• rigorous
• rough
• rugged
• scrupulous
• severe
• spiny
• steep
• stern
• strenuous
• strict
• stringent
• subtle
• taxing
• teasing
• thorny
• ticklish
• toilsome
• tough
• tricky
• trying
• unsparing
• uphill
• urgent
• weighty
• wicked