rust

a red or brown oxide coating on iron or steel caused by the action of oxygen and moisture

a plant disease that produces a reddish-brown discoloration of leaves and stems; caused by various rust fungi

the formation of reddish-brown ferric oxides on iron by low-temperature oxidation in the presence of water

any of various fungi causing rust disease in plants

become destroyed by water, air, or a corrosive such as an acid; "The metal corroded"; "The pipes rusted"

cause to deteriorate due to the action of water, air, or an acid; "The acid corroded the metal"; "The steady dripping of water rusted the metal stopper in the sink"

become coated with oxide

of the brown color of rust