1

rust

play
noun \ ˈrəst \

Definition of rust

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

Examples of rust in a Sentence

  1. an old pump covered in rust

Recent Examples of rust from the Web

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.

Origin and Etymology of rust

Middle English, from Old English rūst; akin to Old English rēad red — more at red


2

rust

verb

Definition of rust

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

  1. Your bicycle will rust if you leave it out in the rain.

  2. The moist air rusted the latch on the door.

  3. The old iron fence was rusted.

Recent Examples of rust from the Web

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.

First Known Use of rust

13th century


RUST Defined for English Language Learners

rust

play
noun

Definition of rust for English Language Learners

  • : 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


rust

verb

Definition of rust for English Language Learners

  • : to form rust : to become rusty

  • : to cause rust to form on (something)


RUST Defined for Kids

1

rust

play
noun \ ˈrəst \

Definition of rust for Students

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

2

rust

verb

Definition of rust for Students

rusted; rusting
:to make or become rusty

Medical Dictionary

rust

play
noun \ ˈrəst \

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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