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English definition of “rust”

rust

noun [U]     /rʌst/
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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