rust

rust is a Noun

Definition:

[1] 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.

[2] 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.

[3] That which resembles rust in appearance or effects. Specifically:

[4] A composition used in making a rust joint. See Rust joint, below.

[5] Foul matter arising from degeneration; as, rust on salted meat.

[6] Corrosive or injurious accretion or influence. Sacred truths cleared from all rust and dross of human mixtures. Eikon Basilike.