demanding
1. [ adjective ] requiring more than usually expected or thought due; especially great patience and effort and skill
Examples:

"found the job very demanding" "a baby can be so demanding"

Related terms: undemanding stern rigorous tightened hard-to-please hard-to-please exigent difficult
Similar spelling:   demandingly
  demand
  demand_loan
  demander
  demantoid
  demand_note