1. Characterized by effort to the point of exhaustion; especially physical effort
   "a gruelling campaign"
   - arduous, backbreaking, grueling [US], hard, heavy, laborious, operose, punishing, toilsome

See also: effortful

• fool's errand
• fool's gold
• fool's huckleberry
• fool's paradise
• fool's parsley
• foolery
• foolhardily
• foolhardiness
• foolhardy
• fooling
• foolish
• foolish woman
• foolishly
• foolishness
• foolproof
• foolscap
• foosball
• foot
• foot brake
• foot doctor
• foot lever
• foot pedal
• foot rot
• foot rule
• foot soldier