rustproof

From rust +‎ -proof.

rustproof (comparative more rustproof, superlative most rustproof)

1. Resistant to rust, oxidation and corrosion.

   Synonyms: nonrusting, stainless

   This is supposed to be a rustproof trashcan, but it can't handle the salt they use on our roads.

2. Resistant to the rust fungus.

rustproof (third-person singular simple present rustproofs, present participle rustproofing, simple past and past participle rustproofed)

1. To make resistant to rust, such as by applying a coating.

   We'll rustproof the metal with a good coat of paint and then we'll be able to leave it outdoors for years without damage.