Rust /(?)/

Rust

n.
  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. (Chem.)
  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. (Bot.)
  3. That which resembles rust in appearance or effects.
    Sacred truths cleared from all rust and dross of human mixtures.
    — Eikon Basilike.

Phrases & Compounds
Rust joint
a joint made between surfaces of iron by filling the space between them with a wet mixture of cast-iron borings, sal ammoniac, and sulphur, which by oxidation becomes hard, and impervious to steam, water, etc.
Rust mite
a minute mite (Phytopius oleivorus) which, by puncturing the rind, causes the rust-colored patches on oranges.

Rust

v. i.

imp. & p. p. Rusted; p. pr. & vb. n. Rusting

  1. To contract rust; to be or become oxidized.
    If gold ruste, what shall iron do?
    Our armors now may rust.
  2. To be affected with the parasitic fungus called rust; also, to acquire a rusty appearance, as plants.
  3. To degenerate in idleness; to become dull or impaired by inaction. Fig.:
    Must I rust in Egypt? never more Appear in arms, and be the chief of Greece?

Rust

v. t.
  1. To cause to contract rust; to corrode with rust; to affect with rust of any kind.
    Keep up your bright swords, for the dew will rust them.
  2. To impair by time and inactivity. Fig.: