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 : accretion2: corrosive or injurious influence or effect3: any of numerous destructive diseases of plants produced by fungi (order Uredinales) and characterized by usually reddish-brown pustular lesions ; also : a fungus causing this4: a strong reddish brown