Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

English definition of “rust”


noun [U]     /rʌst/
a dark orange substance that you get on metal when it has been damaged by air and waterMetals and metalworkingChemical elements
rust verb [I, T]
(Definition of rust noun from the Cambridge Learner's Dictionary © Cambridge University Press)

Definitions of “rust” in other dictionaries

Word of the Day


a document given to students or reporters which contains information about a particular subject

Word of the Day


Read our blog about how the English language behaves.

Learn More

New Words

Find words and meanings that have just started to be used in English, and let us know what you think of them.

Learn More