rusting

To oxidize, especially of iron or steel.

“The patio furniture had rusted in the wind-driven spray.”

To cause to oxidize.

“The wind-driven spray had thoroughly rusted the patio furniture.”

To be affected with the parasitic fungus called rust.

To (cause to) degenerate in idleness; to make or become dull or impaired by inaction.

The development of rust on a surface.