\ 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


an old pump covered in rust


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 rust-belt province of Liaoning, meanwhile, has preferential tax policies for advanced manufacturing and for scientific investment, according to the report. Lingling Wei, WSJ, "China’s Plan for Tech Dominance Is Advancing, Business Groups Say," 22 Jan. 2019 Mistake #3: The Wrong Fastener Using plain steel nails and screws outside is an invitation for corrosion, rust stains, and wood joints that fall apart. Roy Berendsohn, Popular Mechanics, "5 Biggest Woodworking Mistakes (And How to Avoid Them)," 15 Jan. 2019 Several ride manufacturers are providing more information about detecting corrosion, although the department can’t say what percentage of rides are covered by new safety bulletins calling for rust inspections. Julie Carr Smyth, The Seattle Times, "State fair officials work to reassure visitors about safety," 23 July 2018 So a set of rust-red AGA ranges (an icon of 18th-century British kitchen design) were installed underneath breezy open shelving. Amanda Sims, House Beautiful, "Kathryn M. Ireland's Kitchen Is A Treasure Trove Of Design Ideas," 22 Jan. 2019 That decision will come amid mounting complaints by residents of discolored water that smells of chlorine or rust. Angel Jennings,, "Customers sue embattled Compton water district over discolored water," 10 July 2018 Right-hander Chase Anderson scraped off the rust of being idle for two weeks and the Milwaukee Brewers took advantage of the few mistakes made by Zack Greinke at Miller Park on Monday night. Tom Haudricourt, Milwaukee Journal Sentinel, "Brewers 4, Diamondbacks 2: Chase Anderson's solid six innings backed by three home runs," 21 May 2018 Everything has been good, just knocking the rust off and trying to get that movement back. Andrew Lopez,, "LSU football's Andre Anthony more than eager to put his best foot forward," 27 Mar. 2018 This use ends up generating rust and sludge, which can damage the cooling system. Zachary Palmer, Popular Mechanics, "Choosing the Right Coolant for Your Car," 4 Sep. 2018

Recent Examples on the Web: Verb

But after the disintegration of the USSR in 1991, Energia was left rusting in the hangars of Baikonur Cosmodrome in Kazakhstan. Anatoly Zak, Popular Mechanics, "Russia's New Rocket Project Might Resurrect a Soviet-Era Colossus," 24 July 2018 Stall dividers are hung from the ceiling rather than bolted to the floor—easier to clean the floor that way, and there isn’t hardware to rust on the floor. Scott Mccartney, WSJ, "Airports Try Stall Tactic: Better Bathrooms," 2 Jan. 2019 Parts of the roof have caved in, wooden panels are missing and the kitchen stoves have rusted. Lefteris Pitarakis, Fox News, "AP PHOTOS: Istanbul's historic orphanage awaits salvation," 9 Sep. 2018 Two state troopers were handcuffing two lanky, bedraggled guys and had them leaning over the side of their rusted out Dodge Aspen, while two German shepherds sniffed the vehicle. Anne Slowey, Condé Nast Traveler, "Fear and Self-Loathing in the American Southwest," 25 July 2018 In this case, the film showcases a future that looks plenty familiar in anime and science fiction novels: a cluttered, rusted-out world that’s a little cyberpunk, a little steampunk, and a whole lot of classic anime series like Mobile Suit Gundam. Tasha Robinson, The Verge, "The Verge fall movie preview, December 2018," 7 Sep. 2018 This helps keep the bearings from pitting and the internal parts of the engine from rusting. Seth Porges, Popular Mechanics, "8 Clever Uses for Silica Gel," 29 Apr. 2010 Residents who have reddish brown water may have pipes or water heaters that are rusting. Michael Livingston,, "Water quality report offers solutions to inconvenient troubles," 11 July 2018 Sorry in advance if these vehicles depreciate in value just as quickly as that Pontiac Aztek rusting away in your driveway. Nathan Bomey, USA TODAY, "10 hot vehicles most likely to increase in value, 'terrifying the neighbors'," 22 Apr. 2018

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

21 Mar 2019

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Time Traveler for rust

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

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More Definitions for rust



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

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

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