If gold ruste, what shall iron do? --Chaucer.
Our armors now may rust. --Dryden.
2. To be affected with the parasitic fungus called rust;
also, to acquire a rusty appearance. as plants.
3. Fig.: To degenerate in idleness; to become dull or
impaired by inaction.
Must I rust in Egypt? never more Appear in arms, and
be the chief of Greece? --Dryden.
2. (Bot.) 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.
Note: Rust is also applied to many other minute fungi which
infest vegetation, such as the species of {Ustilago},
{Uredo}, and {Lecythea}.
3. That which resembles rust in appearance or effects.
Specifically: (a) A composition used in making a rust
joint. See {Rust joint}, below.
(b) Foul matter arising from degeneration; as, rust on
salted meat.
(c) Corrosive or injurious accretion or influence.
Sacred truths cleared from all rust and dross of
human mixtures. --Eikon
Basilike.
Note: Rust is used in the formation of compounds of obvious
meaning; as, rust-colored, rust-consumed, rust-eaten,
and the like.
{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} (Zo["o]l.), a minute mite ({Phytopius oleivorus})
which, by puncturing the rind, causes the rust-colored
patches on oranges.
Keep up your bright swords, for the dew will rust
them. --Shak.
2. Fig.: To impair by time and inactivity. --Johnson.