n.
Function: intransitive verb
Date: 13th century
1 : to form rust : become oxidized <iron rust s >
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 rust ed >
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