Other forms: rusted; rusting; rusts; rustly

Rust is the reddish-brown stuff that forms over time on metal that's gotten wet. Your dad's beat-up old car probably has some rust on it somewhere.

If you leave your bike out overnight in the rain, it'll be fine — you can dry it off the next day. If you leave it out for several rainy weeks, though, your bike will end up with rust on it. Rust appears as brown spots where the combination of water and oxygen has coated the metal with a compound that chemists call an oxide. Rust, which is also a verb, comes from a Germanic root meaning "redness."

Definitions of rust
  1. noun
    a red or brown oxide coating on iron or steel caused by the action of oxygen and moisture
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    type of:
    ferric oxide
    a red oxide of iron
  2. noun
    the formation of reddish-brown ferric oxides on iron by low-temperature oxidation in the presence of water
    synonyms: rusting
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    type of:
    corroding, corrosion, erosion
    erosion by chemical action
    oxidation, oxidisation, oxidization
    the process of oxidizing; the addition of oxygen to a compound with a loss of electrons; always occurs accompanied by reduction
  3. verb
    become destroyed by water, air, or a corrosive such as an acid
    “The pipes rusted
    synonyms: corrode
    corrode, eat
    cause to deteriorate due to the action of water, air, or an acid
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    eat away, fret
    wear away or erode
    type of:
    crumble, decay, dilapidate
    fall into decay or ruin
  4. verb
    become coated with oxide
    oxidate, oxidise, oxidize
    add oxygen to or combine with oxygen
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    type of:
    oxidate, oxidise, oxidize
    enter into a combination with oxygen or become converted into an oxide
  5. verb
    cause to deteriorate due to the action of water, air, or an acid
    “The steady dripping of water rusted the metal stopper in the sink”
    synonyms: corrode, eat
    become destroyed by water, air, or a corrosive such as an acid
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    type of:
    inflict damage upon
  6. adjective
    of the brown color of rust
    synonyms: rust-brown, rusty
    being, having, or characterized by hue
  7. noun
    any of various fungi causing rust disease in plants
    synonyms: rust fungus
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    show 4 types...
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    Melampsora lini, flax rust, flax rust fungus
    fungus causing flax rust
    Cronartium ribicola, blister rust
    fungus causing white pine blister rust and having a complex life cycle requiring a plant of genus Ribes as alternate host
    Puccinia graminis, wheat rust
    rust fungus that attacks wheat
    Gymnosporangium juniperi-virginianae, apple rust, cedar-apple rust
    rust fungus causing rust spots on apples and pears etc
    type of:
    an organism of the kingdom Fungi lacking chlorophyll and feeding on organic matter; ranging from unicellular or multicellular organisms to spore-bearing syncytia
  8. noun
    a plant disease that produces a reddish-brown discoloration of leaves and stems; caused by various rust fungi
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    blister rust, white pine blister rust, white-pine rust
    any of several diseases of pines caused by rust fungi of the genus Cronartium and marked by destructive invasion of bark and sapwood and producing blisters externally
    type of:
    plant disease
    a disease that affects plants




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