n.
   - a reddish- or yellowish-brown flaking coating of iron oxide that is formed on iron or steel by oxidation, especially in the presence of moisture.
 - a fungal disease of plants which results in reddish or brownish patches.
 - a reddish-brown colour.
 
v.
 be affected with rust.
 
  Derivative
  
  Etymology
  OE rūst, of Gmc origin; rel. to red.