\ 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 rust-resistant piece also comes with a special polyester cover to preserve its design when not in use. Travel + Leisure, "Turn Your Backyard Into a Cozy Vacation Paradise With These 9 Fire Pits," 17 May 2020 All of the furniture is made out of aluminum and plastic with a rust-resistant finish. Jennifer Aldrich, Better Homes & Gardens, "6 Backyard Must-Haves from Bed Bath & Beyond's Outdoor Sale," 15 May 2020 There are two main types of rust that impact pears in Western Oregon, Trellis Rust and Pacific Coast Pear Rust. oregonlive, "Ask an expert: Neighbor’s spraying could affect growth, yield of raspberries," 10 May 2020 Disks—either rust or solid-state—are the most common block devices used as vdev building blocks. Jim Salter, Ars Technica, "ZFS 101—Understanding ZFS storage and performance," 8 May 2020 The heads are made of cast-aluminum, which will help them resist rust. Popular Science, "Gardening tool sets that will help your flowers, herbs, and vegetables thrive," 29 Apr. 2020 The rust-brown pigment that rimmed his eyes for our portraits has since been wiped away, though a thin layer of foundation remains. Devon Abelman, Allure, "How JB Defined His Public and Private Selves," 14 Apr. 2020 Most of these pathogens are fungal and can include Rhizoctonia (brown patch), Fusarium, Pithium, gray leaf spot, dollar spot, rust and others. Dallas News, "Blotches on your grass? Here’s how to heal a diseased lawn," 13 Apr. 2020 Omari came up with a scheme to write the names of the prisoners—using a quill fashioned from a chicken bone and ink blended from rust chipped from the cell bars and blood squeezed from the gums of prisoners diseased by malnutrition. Robin Wright, The New Yorker, "How Much Can the Human Spirit Endure in Isolation?," 8 Apr. 2020 Recent Examples on the Web: Verb Stainless-steel ball-bearings won't rust (even with any fridge spills!) and nonstick tops ensure items stay in place while spinning. Hadley Keller, House Beautiful, "A Lazy Susan Is the Game Changer Your Fridge Needs," 9 Apr. 2020 Stainless tools clean up faster and will never rust, and full-size tools are best for barbequing on an open fire. The Editors, Field & Stream, "Three Things You Need in Your Camp Kitchen," 2 Apr. 2020 Sure, the steel on the building’s facade is rusted in parts. Isabella Kwai, New York Times, "What It’s Like to Be Quarantined on an Island Over Coronavirus Fears," 6 Feb. 2020 If your pan is rusted out, take some steel wool to it and scrub that red color off. Sara Chodosh, Popular Science, "Seasoning your cast iron pan isn’t enough," 8 Nov. 2019 These can cause the bike to creak and rust internally. Tyghe Trimble, Popular Mechanics, "Keep Your Bike Ride Ready With a DIY Tune-Up," 24 Apr. 2020 On this Palm Sunday, McGehee delivered his Holy Ghost sermon to the small group sat on grey rusting foldout chairs in the crime-rich, money-poor neighborhood of Toulminville, north of Mobile. Christopher Harress |, al, "Coronavirus brings Holy Week challenges, opportunity for a small Mobile church," 7 Apr. 2020 Climbing higher, the tour came upon several crude, rusting metal shacks, nearly swallowed by the brush. San Antonio Express-News, "“It’s almost like having a national park all to yourself.”," 18 Oct. 2019 The timber structure is topped with rusting pipes and valves where the barges would empty their cargo. Peter Marteka,, "Glastonbury to preserve a piece of its Connecticut River history," 11 Sep. 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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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

29 May 2020

Cite this Entry

“Rust.” Dictionary, Merriam-Webster, Accessed 2 Jun. 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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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

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