rusting (Noun) — The formation of reddish-brown ferric oxides on iron by low-temperature oxidation in the presence of water.
rusting (Verb) — Become destroyed by water, air, or a corrosive such as an acid. ex. "The pipes rusted"
rusting (Verb) — Cause to deteriorate due to the action of water, air, or an acid. ex. "The steady dripping of water rusted the metal stopper in the sink"
rusting (Verb) — Become coated with oxide.