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rust

noun [U]
 
 
/rʌst/

Definition

a reddish-brown substance that forms on the surface of iron and steel as a result of reacting with air and water: patches of rustPhysical and chemical processes a reddish-brown colour that looks like rustLess common coloursCommon colours any of various plant diseases that cause reddish-brown spotsPlant pathology rust
 
 
adjective
having a reddish-brown colour
(Definition of rust noun from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press)
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