Main Entry: ¹rust

Pronunciation: \ˈrəst\

Function: noun

Etymology: Middle English, from Old English rūst; akin to Old English rēad red — more at red

Date: before 12th century

1 a : the reddish brittle coating formed on iron especially when chemically attacked by moist air and composed essentially of hydrated ferric oxide b : a comparable coating produced on a metal other than iron by corrosion c : something resembling rust : accretion
2 : corrosive or injurious influence or effect
3 : any of numerous destructive diseases of plants produced by fungi (order Uredinales) and characterized by usually reddish-brown pustular lesions; also : a fungus causing this
4 : a strong reddish brown