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.-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.-that which resembles rust in appearance or effects.-a composition used in making a rust joint. see rust joint, below.-foul matter arising from degeneration; as, rust on salted meat.-corrosive or injurious accretion or influence.-to contract rust; to be or become oxidized.-to be affected with the parasitic fungus called rust; also, to acquire a rusty appearance, as plants.-to degenerate in idleness; to become dull or impaired by inaction.-to cause to contract rust; to corrode with rust; to affect with rust of any kind.-to impair by time and inactivity.