\ 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

Using a razor that is dry, sharp, and rust-free will always give you the closest, cleanest shave possible. Deanna Pai, Glamour, "How to Shave Your Legs Perfectly," 30 June 2019 Stainless-steel clouds ring the top of the rust-brown structure, which was erected after the original two towers had to be relocated with the construction of State Route 125. Martina Schimitschek, San Diego Union-Tribune, "Fletcher Hills: A long-established neighborhood with easy access to freeways, shopping and good schools," 30 June 2019 Working evenings as a janitor for meager wages helped me get through college in the daytime and kept gas in my rust-bucket car. WSJ, "The $15 Minimum Wage and Restaurants," 28 June 2019 By the early 1900s sleek and rust-resistant stainless steel started to make an appearance. Hannah Whitaker, National Geographic, "Why carrying your own fork and spoon helps solve the plastic crisis," 28 June 2019 Climbing to the top of the Urucum plateau, a shock of rust-red land thrust 1 kilometer above the Brazilian savanna, is a journey into Earth's deep past. Paul Voosen, Science | AAAS, "Dinosaur-age landscapes lurk in Southern Hemisphere," 26 June 2019 If your point of comparison is conventional hard disks, this doesn't matter too much; a good SSD will typically have five or six times the throughput and 10,000 times the IOPS of even a very fast rust disk. Jim Salter, Ars Technica, "Digging into the new features in OpenZFS post-Linux migration," 20 June 2019 Uni has a tang of iodine, sometimes, and is always a treat for the eye, as rust-orange as the Golden Gate Bridge and protected by its carapace of spines (black-red or purple from the West Coast, sometimes green-tinged from the East). Bill St. John, The Denver Post, "Preparing uni and lobster," 19 June 2019 Despite this, Mr Trump and his advisers are convinced that the world order is rigged against America, pointing to its rust-belt and its trade deficit. The Economist, "America is deploying a new economic arsenal to assert its power," 6 June 2019

Recent Examples on the Web: Verb

An unspecified number were intact; others had rusted out. Rob Davis | The Oregonian/oregonlive,, "U.S. EPA finds 18 barrels, some intact, in Wallowa Lake recovery effort," 14 June 2019 Metal catheters may begin to rust or decompose within the bear’s body. National Geographic, "Bear bile, explained," 12 June 2019 Even the slightest bit of dampness will cause the pan to rust. Joseph Truini, Popular Mechanics, "How To Clean a Cast-Iron Pan," 3 June 2019 Chen’s volunteers live on the property in prefab homes, a camper and stables on whose walls rusted riding gear still hangs. Matthew Ormseth,, "With Tiananmen Square ‘Tank Man,’ Chinese sculptor will keep democracy’s flame alive in Mojave," 3 June 2019 There’s diversity in the reason the inspector fired Stop Sales. Dented or rusted 6-pound cans of ketchup. David J. Neal, miamiherald, "Two-hundred rodent poops. Roaches in a microwave. Why these restaurants failed inspection," 4 June 2019 The national railway, like Ozymandias’ statue, rusted in the wilderness. Charles R. Morris, WSJ, "‘The Longest Line on the Map’ Review: The End of the Road," 8 Jan. 2019 Start at the stairs adjacent to the modern rusted-steel facade of the Gulch Crossing building on Demonbreun Street. Christian L. Wright, WSJ, "A Guide to Nashville’s Chicest New Neighborhood," 5 Mar. 2019 The basketball hoops had worn nets, and the swing set had rusted handles, with one of the seats detached. New York Times, "What Budget Cuts Mean for Third Graders in a Rural School," 5 June 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

11 Jul 2019

Look-up Popularity

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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