Definition of rust

• n. - The reddish yellow coating formed on iron when exposed to moist air, consisting of ferric oxide or hydroxide; hence, by extension, any metallic film of corrosion.
• n. - A minute mold or fungus forming reddish or rusty spots on the leaves and stems of cereal and other grasses (Trichobasis Rubigo-vera), now usually believed to be a form or condition of the corn mildew (Puccinia graminis). As rust, it has solitary reddish spores; as corn mildew, the spores are double and blackish.
• n. - That which resembles rust in appearance or effects.
• n. - A composition used in making a rust joint. See Rust joint, below.
• n. - Foul matter arising from degeneration; as, rust on salted meat.
• n. - Corrosive or injurious accretion or influence.
• v. i. - To contract rust; to be or become oxidized.
• v. i. - To be affected with the parasitic fungus called rust; also, to acquire a rusty appearance, as plants.
• v. i. - To degenerate in idleness; to become dull or impaired by inaction.
• v. t. - To cause to contract rust; to corrode with rust; to affect with rust of any kind.
• v. t. - To impair by time and inactivity.