\ ˈrəst How to pronounce rust (audio) \

Definition of rust

 (Entry 1 of 2)

1a : the reddish brittle coating formed on iron especially when chemically attacked by moist air and composed essentially of hydrated ferric oxide
b : a comparable coating produced on a metal other than iron by corrosion
c : something resembling rust : accretion
2 : corrosive or injurious influence or effect
3 : any of numerous destructive diseases of plants produced by fungi (order Uredinales) and characterized by usually reddish-brown pustular lesions also : a fungus causing this
4 : a strong reddish brown


rusted; rusting; rusts

Definition of rust (Entry 2 of 2)

intransitive verb

1 : to form rust : become oxidized iron rusts
2 : to degenerate especially from inaction, lack of use, or passage of time most men would … have allowed their faculties to rust— T. B. Macaulay
3 : to become reddish brown as if with rust the leaves slowly rusted
4 : to be affected with a rust fungus

transitive verb

1 : to cause (a metal) to form rust keep up your bright swords, for the dew will rust them— William Shakespeare
2 : to impair or corrode by or as if by time, inactivity, or deleterious use
3 : to cause to become reddish brown : turn the color of rust

Examples of rust in a Sentence

Noun an old pump covered in rust Verb Your bicycle will rust if you leave it out in the rain. The moist air rusted the latch on the door. The old iron fence was rusted.
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Recent Examples on the Web: Noun The important thing is to abrade off shiny spots, rust, deep scratches, and the like. Dan Roe, Popular Mechanics, "Things Come Apart: Milwaukee Cordless Band Saw," 20 Oct. 2019 On its website, NHTSA explains that vehicles are not recalled for cosmetic problems, rust, excessive oil use or normal wear. NBC News, "How to make sure a used car is safe," 15 Oct. 2019 Murray eventually knocked off some rust to post a solid game, even swishing a few jump shots to boot. Jeff Mcdonald,, "Derrick White’s summer abroad could pay dividends for Spurs’ bench," 5 Oct. 2019 Neither veteran can take time to knock off the rust against an Auburn offense loaded with playmakers. Edgar Thompson,, "UF QB Kyle Trask maintaining poise among five keys for No. 10 Gators against No. 7 Auburn," 1 Oct. 2019 That Cord needs to shake off some rust leaves the door slightly open for Henderson, a junior college transfer in his second season in the program, and perhaps even to Bachmeier, who enrolled early and participated in spring drills. Paul Myerberg, USA TODAY, "The 10 biggest quarterback competitions in college football during fall camp," 6 Aug. 2019 Noticeable rust on the inside of meat grinder and blades. Ebony Day, azcentral, "Rusty hooks used to hang ducks among violations found in restaurant inspections," 3 July 2019 For most of her nearly seven-year tenure as CEO, Ms. Rometty has tried to shake the rust off the aging tech giant with bets on emerging opportunities such as artificial intelligence and the blockchain, some of which have yet to pay out. Jay Greene, WSJ, "IBM’s Rometty Bets Her Legacy on Red Hat Deal," 29 Oct. 2018 James helped make Cleveland, a hardscrabble rust-belt town known for its roll-up-your-sleeves, blue-collar style, intriguing on the national level. Fortune, "Could Baker Mayfield and Odell Beckham, Jr. Be Worth More to Cleveland Than LeBron?," 7 Sep. 2019 Recent Examples on the Web: Verb The trestle has sat unused since the streetcar shut down in 1962, and its age shows; sections of the steel supports have rusted away and wooden ties have fallen. Luz Lazo, Washington Post, "D.C.’s last trolley trestle is in ‘imminent risk of collapse’," 17 Jan. 2018 Cast-iron rails rusted and sometimes failed under stress. Kevin Leonard,, "The dream of electric trains has origins in Laurel," 6 Sep. 2019 Eerie footage of the dive obtained by the BBC shows the Titanic’s rusting bow and parts of the ship’s wrecked hull. Fox News, "New Titanic images show the wreck’s 'shocking' deterioration," 22 Aug. 2019 The siren’s horn is where the light would be in a functioning lighthouse.(File Photo) Newport Beach will replace its tsunami warning alarms because its current sirens rusted. Hillary Davis, Daily Pilot, "Newport Beach to replace rusty tsunami warning sirens," 20 Aug. 2019 Clean-up efforts will extend to removing brush hiding unattended graves dating back to the 1860s that border rusted barbed wire lining the cemetery’s edge, above Salado Creek. Vincent T. Davis,, "Once in ruins, San Antonio’s Eastview Cemetery restored to sacred resting place," 15 Aug. 2019 The lawsuit includes a letter from 2012 that appears to have been sent by KMG to another ride operator in Canada that discusses the possibility of rusting. Washington Post, "Lawsuit: Thrill ride maker knew of defect before fatal crash," 5 June 2019 Once abandoned and rusting away, the Cordray's have breathed new life into the property. Rebecca Hennes, Houston Chronicle, "Before and after photos show dramatic transformation of Galveston Island's Kettle House," 1 July 2019 During the process, the bears are usually kept in tiny cages and live with a permanent catheter, to drain the bile, that can rust or otherwise degrade. Jani Actman, National Geographic, "How can traditional Chinese medicine threaten wildlife?," 17 June 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'rust.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of rust


before the 12th century, in the meaning defined at sense 1a


13th century, in the meaning defined at intransitive sense 1

History and Etymology for rust


Middle English, from Old English rūst; akin to Old English rēad red — more at red

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Statistics for rust

Last Updated

14 Nov 2019

Time Traveler for rust

The first known use of rust was before the 12th century

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More Definitions for rust


How to pronounce rust (audio)

English Language Learners Definition of rust

 (Entry 1 of 2)

: a reddish substance that forms on iron or some other metal usually when it comes in contact with moisture or air
: a disease that causes plants to develop reddish-brown spots
: a reddish-brown color



English Language Learners Definition of rust (Entry 2 of 2)

: to form rust : to become rusty
: to cause rust to form on (something)


\ ˈrəst How to pronounce rust (audio) \

Kids Definition of rust

 (Entry 1 of 2)

1 : a reddish coating formed on metal (as iron) when it is exposed especially to moist air
2 : a plant disease caused by fungi that makes spots on plants
3 : a fungus that causes a rust


rusted; rusting

Kids Definition of rust (Entry 2 of 2)

: to make or become rusty


\ ˈrəst How to pronounce rust (audio) \

Medical Definition of rust

1 : the reddish brittle coating formed on iron especially when chemically attacked by moist air and composed essentially of hydrated ferric oxide
2 : any of numerous destructive diseases of plants produced by fungi (order Uredinales) and characterized by reddish brown pustular lesions also : a fungus causing this

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More from Merriam-Webster on rust

Thesaurus: All synonyms and antonyms for rust

Rhyming Dictionary: Words that rhyme with rust

Spanish Central: Translation of rust

Nglish: Translation of rust for Spanish Speakers

Britannica English: Translation of rust for Arabic Speakers Encyclopedia article about rust

Comments on rust

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not being in agreement or harmony

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