\ 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 There was just bound to be some rust on IU’s aerial attack coming into the season. Jon Blau, The Indianapolis Star, "IU football: QB Michael Penix, aggressive defense shine," 2 Nov. 2020 Featuring a ceramic rust-resistant blade, it can be used wet or dry and prevents nicks in the most sensitive of areas. Fiona Tapp, CNN Underscored, "Our favorite picks from the Amazon Canada holiday gift guide," 29 Oct. 2020 Every element of the best-seller is taken into account, from the rust-resistant metal grommets to the unique ultra-smooth design that repels water for a faster dry. Braelyn Wood,, "Your Shower Curtain Has More Germs Than Your Toilet—But This $11 Product Can Change That," 26 Oct. 2020 The good news for Kentucky is the defensive showing at Auburn was good enough to think if Wilson’s first-game mistakes can be fixed with more snaps to shake off rust, this team is good enough to compete with every team on the schedule. Jon Hale, The Courier-Journal, "Wild first day of SEC football shows anything is still possible for Kentucky in 2020," 27 Sep. 2020 Owen Pappoe knew Auburn’s defense would need to shake off some rust against Kentucky after going nearly nine months between games. Tom Green |, al, "Auburn’s defense didn’t panic after troublesome start on 3rd downs," 27 Sep. 2020 Miami is expected to compete for an ACC title this season with star transfer quarterback D’Eriq King, but the Hurricanes face a UAB team that already had a chance to shake off some rust in a 45-35 win over Central Arkansas last week. C.j. Doon,, "Most intriguing Week 1 college football questions: How prepared will teams be for actual games?," 9 Sep. 2020 How did the guard shake off the rust from months without access to the Mavericks’ practice facility? Callie Caplan, Dallas News, "5 things we learned from the Mavericks’ scrimmages in NBA bubble ahead of restart opener vs. Rockets," 31 July 2020 Some of the rust has shaken off now that practices have been consistent. Alex Vejar, The Salt Lake Tribune, "Utah State’s goal is a Mountain West football title, but with many new faces, Aggies will have to gel in a hurry," 22 Oct. 2020 Recent Examples on the Web: Verb Lightweight ball bearing reel with aluminum spool that won't rust. Bob Beacham,, "The best ice fishing rod," 17 Oct. 2020 Moisture can causemoving parts to rust and seize up. Peter Krouse, cleveland, "Tips for storing your bicycle this winter," 17 Oct. 2020 The Aurora’s luster had largely faded when Willson got his first look, rust and rot taking hold. Kurtis Alexander, San Francisco Chronicle, "Shipwrecked on Little Potato Slough," 8 Oct. 2020 The metal will rust if it’s not wiped down with a thin layer of oil after washing. Paul Stephen,, "Paul’s Cooking Tips: How to use a paella pan for biscuits, stir fry, roasting chicken and more," 26 Sep. 2020 As Wilson plays more, he can be expected to fix many of the mistakes that could be attributed to rust Saturday. Jon Hale, The Courier-Journal, "Kentucky football falls in opener at Auburn after series of late mistakes," 26 Sep. 2020 Many parents like the natural appeal of wooden swing sets, as well as their resistance to rust. Sian Babish,, "The best swing set of 2020," 22 Sep. 2020 Completely untreated raw sheet steel can rust through in as little as a few years. Ben Wojdyla, Popular Mechanics, "How to Prevent and Remove Rust on Your Car Like a Pro," 8 Sep. 2020 So, what exactly is causing the moon to rust like an old jalopy sitting in a junkyard? Jennifer Nalewicki, Smithsonian Magazine, "Why Is the Moon Covered in Rust? Even Scientists Are Stumped by This Metal Mystery," 9 Sep. 2020

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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Time Traveler for rust

Time Traveler

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

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Statistics for rust

Last Updated

11 Nov 2020

Cite this Entry

“Rust.” Dictionary, Merriam-Webster, Accessed 30 Nov. 2020.

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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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