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English definition of “rust”

rust

noun [U] uk   /rʌst/ us  
a reddish-brown substance that forms on the surface of iron and steel as a result of reacting with air and water: patches of rust a reddish-brown colour that looks like rust any of various plant diseases that cause reddish-brown spots
rust
adjective uk   us  
having a reddish-brown colour

rust

verb [I or T] uk   /rʌst/ us  
to become or cause something to become covered with rust: Older cars will begin to rust. Years of being left out in the rain had rusted the metal chairs. The floor of the car had rusted away/through (= been destroyed by rust), so I was careful where I put my feet.
(Definition of rust from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
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