rust

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Any of various powdery or scaly reddish-brown or reddish-yellow hydrated ferric oxides formed on iron and iron-containing materials by low-temperature oxidation in the presence of water.
2. n. Any of various metallic coatings, especially oxides, formed by corrosion.
3. n. A stain or coating resembling iron rust.
4. n. Deterioration, as of ability, resulting from inactivity or neglect.
5. n. Botany Rust fungus.
6. n. Botany A plant disease caused by a rust fungus, characterized by reddish or brownish spots on leaves, stems, and other parts.
7. n. A strong brown.
8. v. To become corroded.
9. v. To deteriorate or degenerate through inactivity or neglect.
10. v. To become the color of rust.
11. v. Botany To develop a disease caused by a rust fungus.
12. v. To corrode or subject (a metal) to rust formation.
13. v. To impair or spoil, as by misuse or inactivity.
14. v. To color (something) a strong brown.

Century Dictionary and Cyclopedia

1. n. The red or orange-yellow coating which is formed on the surface of iron when exposed to air and moisture; red oxid of iron; in an extended sense, any metallic oxid forming a coat on the metal. Oil-paint, varnish. plumbago, a film of caoutchouc, or a coating of tin may be employed, according to circumstances, to prevent the rusting of iron utensils.
2. n. In metal-working, a composition of iron-filings and sal ammoniac, with sometimes a little sulphur, moistened with water and used for filling fast joints. Oxidation rapidly sets in, and the composition, after a time, becomes very hard, and takes thorough hold of the surfaces between which it is placed. A joint formed in this way is called a rust-joint.
3. n. In botany, a fungous growth on plants which resembles rust on metal; plant-disease caused by fungi of the class Uredineæ (which see, for special characterization): same as brand, 6. See Fungi, mildew, Puccinia, and Trichobasis; also black rust and red rust, below.
4. n. Any foul extraneous matter; a corrosive, injurious, or disfiguring accretion.
5. n. Any growth, influence, or habit tending to injure the mental or moral faculties; a habit or tendency which clogs action or usefulness; also, the state of being affected with such a habit.
6. To contract or gather rust; be oxidized.
7. To assume an appearance of rust, or as if coated with rust.
8. To degenerate in idleness; become dull through inaction.
9. To cause to contract rust.
10. To impair by time and inactivity.
11. An obsolete variant of roost.
12. n. Rust formed on iron by exposure to air and water often approaches pretty closely in composition the mineral limonite, a ferric oxyhydroxid (Fe₄O₃(HO)₆). It also frequently contains some ferrous or ferrosoferric oxid and hydroxid, and is more or less perceptibly magnetic.

Wiktionary

1. n. The deteriorated state of iron or steel as a result of moisture and oxidation.
2. n. A reddish-brown color.
3. n. A disease of plants caused by a reddish-brown fungus.
4. v. intransitive to oxidize, especially of iron or steel.
5. v. transitive to cause to oxidize.

GNU Webster's 1913

1. n. (Chem.) 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. n. (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.
3. n. That which resembles rust in appearance or effects. A composition used in making a rust joint. See Rust joint, below.
4. n. Foul matter arising from degeneration.
5. n. Corrosive or injurious accretion or influence.
6. v. To contract rust; to be or become oxidized.
7. v. To be affected with the parasitic fungus called rust; also, to acquire a rusty appearance, as plants.
8. v. To degenerate in idleness; to become dull or impaired by inaction.
9. v. To cause to contract rust; to corrode with rust; to affect with rust of any kind.
10. v. To impair by time and inactivity.

WordNet 3.0

1. v. become coated with oxide
2. v. become destroyed by water, air, or a corrosive such as an acid
3. v. cause to deteriorate due to the action of water, air, or an acid
4. n. a red or brown oxide coating on iron or steel caused by the action of oxygen and moisture
5. n. the formation of reddish-brown ferric oxides on iron by low-temperature oxidation in the presence of water
6. n. a plant disease that produces a reddish-brown discoloration of leaves and stems; caused by various rust fungi
7. n. any of various fungi causing rust disease in plants
8. adj. of the brown color of rust