from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun Any of various powdery or scaly reddish-brown or reddish-yellow hydrated ferric oxides and hydroxides formed on iron and iron-containing materials by low-temperature oxidation in the presence of water.
  • noun Any of various metallic coatings, especially oxides, formed by corrosion.
  • noun A stain or coating resembling iron rust.
  • noun Deterioration, as of ability, resulting from inactivity or neglect.
  • noun Rust fungus.
  • noun A plant disease caused by a rust fungus, characterized by reddish or brownish spots on leaves, stems, and other parts.
  • noun A strong brown.
  • intransitive verb To become corroded.
  • intransitive verb To deteriorate or degenerate through inactivity or neglect.
  • intransitive verb To become the color of rust.
  • intransitive verb Botany To develop a disease caused by a rust fungus.
  • intransitive verb To corrode or subject (a metal) to rust formation.
  • intransitive verb To impair or spoil, as by misuse or inactivity.
  • intransitive verb To color (something) a strong brown.

from The Century Dictionary.

  • To contract or gather rust; be oxidized.
  • To assume an appearance of rust, or as if coated with rust.
  • To degenerate in idleness; become dull through inaction.
  • To cause to contract rust.
  • To impair by time and inactivity.
  • An obsolete variant of roost.
  • noun 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.
  • noun 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.
  • noun 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.
  • noun Any foul extraneous matter; a corrosive, injurious, or disfiguring accretion.
  • noun 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.
  • noun 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.

from the GNU version of the Collaborative International Dictionary of English.

  • noun (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.
  • noun (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.
  • noun That which resembles rust in appearance or effects.
  • noun Foul matter arising from degeneration.
  • noun Corrosive or injurious accretion or influence.
  • noun 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.
  • noun (Zoöl.) a minute mite (Phytopius oleivorus) which, by puncturing the rind, causes the rust-colored patches on oranges.
  • transitive verb To cause to contract rust; to corrode with rust; to affect with rust of any kind.
  • transitive verb To impair by time and inactivity.
  • intransitive verb To contract rust; to be or become oxidized.
  • intransitive verb To be affected with the parasitic fungus called rust; also, to acquire a rusty appearance, as plants.
  • intransitive verb To degenerate in idleness; to become dull or impaired by inaction.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun The deteriorated state of iron or steel as a result of moisture and oxidation.
  • noun A reddish-brown color.
  • noun A disease of plants caused by a reddish-brown fungus.
  • verb intransitive to oxidize, especially of iron or steel.
  • verb transitive to cause to oxidize.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • verb become coated with oxide
  • verb become destroyed by water, air, or a corrosive such as an acid
  • verb cause to deteriorate due to the action of water, air, or an acid
  • noun a red or brown oxide coating on iron or steel caused by the action of oxygen and moisture
  • noun the formation of reddish-brown ferric oxides on iron by low-temperature oxidation in the presence of water


from The American Heritage® Dictionary of the English Language, 4th Edition

[Middle English, from Old English rūst; see reudh- in Indo-European roots.]

from Wiktionary, Creative Commons Attribution/Share-Alike License

Old English rūst, from Proto-Germanic *rusta-. Related to red. Cognates include Dutch roest, German Rost and Danish rust.


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  • used as a colour, by Sylvia Plath.

    as a noun, referring to iron oxide, a rough but fragile corruption of a once strong metal, broken by the elements.

    March 12, 2009