rust

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

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

(noun) the formation of reddish-brown ferric oxides on iron by low-temperature oxidation in the presence of water. Synonyms: rusting.

(noun) any of various fungi causing rust disease in plants. Synonyms: rust fungus.

(verb) become destroyed by water, air, or a corrosive such as an acid. Synonyms: corrode. Examples: "The metal corroded." "The pipes rusted."

(verb) cause to deteriorate due to the action of water, air, or an acid. Synonyms: corrode, eat. Examples: "The acid corroded the metal." "The steady dripping of water rusted the metal stopper in the sink."

(verb) become coated with oxide.

(adj) of the brown color of rust. Synonyms: rusty, rust-brown.