Rust  —n. 1 reddish corrosive coating formed on iron, steel, etc. By oxidation, esp. When wet. 2 fungal plant-disease with rust-coloured spots. 3 impaired state due to disuse or inactivity. 4 reddish-brown. —v. 1 affect or be affected with rust. 2 become impaired through disuse. [old english]