rust

verb

rusted; rusting; rusts

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

Years of storage in the damp basement rusted the tools.

3

: to cause to become reddish brown : turn the color of rust

Examples of rust in a Sentence

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 Web

Just keep in mind that saltwater systems can cause metal parts to rust over time. —Chaunie Brusie, Parents, 6 June 2026

The post-wash rub will help the oil build up over time, which keeps the pan non-stick and from rusting. —Katherine McLaughlin, Architectural Digest, 4 June 2026

While statistics suggest that Bass has made headway on homelessness, makeshift encampments and rows of rusting RVs remain commonplace across the city. —Michael R. Blood, Fortune, 2 June 2026

My French and Dutch rusted like old bicycles. —Joseph O’Neill, New Yorker, 1 June 2026

Word History

First Known Use

13th century, in the meaning defined at intransitive sense 1

Phrases Containing rust

• anti-rust
• blister rust
• cedar-apple rust
• crown rust
• leaf rust
• red rust
• rust belt
• rust bucket
• rust mite
• stem rust
• wheat rust
• white-pine blister rust
• white rust

Rhymes for rust

• bused
• bust
• crust
• cussed
• dust
• fussed
• fust
• gust
• just
• lust
• maist
• mussed

Kids Definition

rust

1 of 2 noun

ˈrəst 

1

: 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

noun

ˈrəst 

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 Pucciniales) and characterized by reddish brown pustular lesions

also : a fungus causing this