noun
    
    [noncount] a reddish substance that forms on iron or some other metal usually when it comes in contact with moisture or air
    
    
    
    
    
    a disease that causes plants to develop reddish-brown spots
    
    a reddish-brown color
    
    verb
    
    rusts; rusted; rusting
    
    [no obj] :to form rust :to become rusty
    
    
    
    
    
    
    
    [+ obj] :to cause rust to form on (something)