• synonyms


  1. Also called iron rust. the red or orange coating that forms on the surface of iron when exposed to air and moisture, consisting chiefly of ferric hydroxide and ferric oxide formed by oxidation.
  2. any film or coating on metal caused by oxidation.
  3. a stain resembling this coating.
  4. any growth, habit, influence, or agency tending to injure, deteriorate, or impair the mind, character, abilities, usefulness, etc.
  5. Plant Pathology.
    1. any of several diseases of plants, characterized by reddish, brownish, or black pustules on the leaves, stems, etc., caused by fungi of the order Uredinales.
    2. Also called rust fungus.a fungus causing this disease.
    3. any of several other diseases of unknown cause, characterized by reddish-brown spots or discolorations on the affected parts.
  6. reddish yellow, reddish brown, or yellowish red.
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verb (used without object)
  1. to become or grow rusty, as iron.
  2. to contract rust.
  3. to deteriorate or become impaired, as through inaction or disuse.
  4. to become rust-colored.
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verb (used with object)
  1. to affect with rust.
  2. to impair as if with rust.
  3. to make rust-colored.
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  1. having the color rust.
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Verb Phrases
  1. rust out, (of metal pipes, machinery, etc.) to decay and become unusable through the action of rust.
  2. rust through, to develop holes, breaks, or the like, because of rust.
  3. rust together, to join two metal pieces, as iron pipes, by causing the joint to rust.
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Origin of rust

before 900; (noun) Middle English; Old English rūst; cognate with German Rost; (v.) Middle English rusten, derivative of the noun; akin to red1
Related formsde·rust, verb (used with object)un·rust, verb (used with object)

Synonyms for rust

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for unrusted

Historical Examples of unrusted

  • He cleaned a piece, which shone bright and unrusted in the moonlight, and touched it with his tongue.

    The Gold Of Fairnilee

    Andrew Lang

British Dictionary definitions for unrusted


  1. a reddish-brown oxide coating formed on iron or steel by the action of oxygen and moisture
  2. Also called: rust fungus plant pathol
    1. any basidiomycetous fungus of the order Uredinales, parasitic on cereal plants, conifers, etc
    2. any of various plant diseases characterized by reddish-brown discoloration of the leaves and stem, esp that caused by the rust fungi
    1. a strong brown colour, sometimes with a reddish or yellowish tinge
    2. (as adjective)a rust carpet
  3. any corrosive or debilitating influence, esp lack of use
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  1. to become or cause to become coated with a layer of rust
  2. to deteriorate or cause to deteriorate through some debilitating influence or lack of usehe allowed his talent to rust over the years
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Derived Formsrustless, adjective

Word Origin for rust

Old English rūst; related to Old Saxon, Old High German rost
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for unrusted



"red oxide of iron," Old English rust "rust; moral canker," related to rudu "redness," from Proto-Germanic *rusta- (cf. Frisian rust, Old High German and German rost, Middle Dutch ro(e)st), from PIE *reudh-s-to- (cf. Lithuanian rustas "brownish," rudeti "to rust;" Latin robigo, Old Church Slavonic ruzda "rust"), from root *reudh- "red" (see red (adj.1)).

As a plant disease, attested from mid-14c. Rust Belt "decayed urban industrial areas of mid-central U.S." (1984) was popularized, if not coined, by Walter Mondale's presidential campaign.

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early 13c., from rust (n.). Transitive sense "cause to rust" is from 1590s. Related: Rusted; rusting.

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Online Etymology Dictionary, © 2010 Douglas Harper

unrusted in Medicine


  1. Any of a group of parasitic fungi of the order Uredinales that are plant pathogens, especially of cereal grains, and that can produce allergy in humans when inhaled in large numbers.
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The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

unrusted in Science


  1. Any of the various reddish-brown oxides of iron that form on iron and many of its alloys when they are exposed to oxygen in the presence of moisture.
    1. Any of various basidiomycete fungi that are parasitic on plants and produce reddish or brownish spots on leaves. Rusts attack a wide variety of plants and can cause enormous damage to crops.
    2. Any of the various plant diseases caused by these fungi.
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  1. To become corroded or oxidized.
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.