rust

I. 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 II. verb Date: 13th century intransitive verb 1. to form rust ; become oxidized <

iron rusts

> 2. to degenerate especially from inaction, lack of use, or passage of time <

most men would…have allowed their faculties to rust — T. B. Macaulay

> 3. to become reddish brown as if with rust <

the leaves slowly rusted

> 4. to be affected with a rust fungus transitive verb 1. to cause (a metal) to form rust <

keep up your bright swords, for the dew will rust them — Shakespeare

> 2. to impair or corrode by or as if by time, inactivity, or deleterious use 3. to cause to become reddish brown ; turn the color of rust