ˈ ̷ ̷ ̷ ̷ˌ ̷ ̷ noun
Etymology: Middle English waterwal, from water + wal wall — more at wall
1. : a wall built beside or around a body of water
2. : an arrangement of pipes carrying water and so grouped as to form a protective wall between a fire (as in a boiler) and the lining of a furnace