1
a
: 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
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
T. B. Macaulay3
: to become reddish brown as if with rust
the leaves slowly rusted
4
: to be affected with a rust fungus
1
: to cause (a metal) to form rust
keep up your bright swords, for the dew will rust them—William Shakespeare
William Shakespeare2
: 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.
Recent Examples on the WebJolie Kerr, Better Homes & Gardens, 15 Aug. 2024
Whether you’re headed to the rust red maw of the Grand Canyon or the wooded summits of Great Smoky Mountains, loads of new hotels and glamping retreats are popping up to meet the demands of park visitors, whose numbers have exploded since the pandemic.
—Emily Pennington, Outside Online, 8 Aug. 2024
Erin Clements, Peoplemag, 31 July 2024
The weather-resistant material can also withstand being left outside in the rain without rusting or peeling.
—Melony Forcier, Travel + Leisure, 16 July 2024
See all Example Sentences for rust 
Noun
Bon Ami, Bar Keepers Friend, and The Pink Stuff are mild abrasives that are particularly effective at removing mineral and rust stains from hard, nonporous surfaces.
—Jolie Kerr, Better Homes & Gardens, 15 Aug. 2024
Whether you’re headed to the rust red maw of the Grand Canyon or the wooded summits of Great Smoky Mountains, loads of new hotels and glamping retreats are popping up to meet the demands of park visitors, whose numbers have exploded since the pandemic.
—Emily Pennington, Outside Online, 8 Aug. 2024
Verb
Photos and video of the property in its current state published by the New Yorker in July, show the ocean-facing facade with all the windows removed and its railings rusting in the open air.
—Erin Clements, Peoplemag, 31 July 2024
The weather-resistant material can also withstand being left outside in the rain without rusting or peeling.
—Melony Forcier, Travel + Leisure, 16 July 2024
See all Example Sentences for rust
These examples are programmatically compiled from various online sources to illustrate current usage of the word 'rust.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.
Dictionary Entries Near rust
Cite this Entry
“Rust.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/rust. Accessed 19 Aug. 2024.
Copy CitationKids Definition
rust
1 of 2 noun1
: a reddish brittle coating formed on iron especially when chemically attacked by moist air and composed chiefly of ferric oxide
2
a
: any of numerous destructive diseases of plants caused by fungi and characterized by reddish brown spots
b
: any of an order of fungi that cause plant rusts
3
: a reddish brown
rust
2 of 2 verb
: to form or cause to form rust
iron rusts
Medical Definition
rust
noun1
: 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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