Rustproof is a term generally used to describe something that is resistant to rust or corrosion. However, there are several other synonyms for this word, including corrosion-resistant, anti-rust, anti-corrosion, and rust-inhibiting.
Corrosion-resistant refers to materials that are chemically stable and therefore impervious to the effects of rust. Anti-rust products are those that have been treated with chemical or mechanical agents to prevent rust formation. Anti-corrosion, on the other hand, is the prevention of any type of corrosion, not just rust. Finally, rust-inhibiting products contain chemical compounds that slow down the process of rust formation and protect the metal from damage.
In conclusion, rustproof may be the most commonly used term to describe rust resistant objects, but there are several other words used that have the same meaning and implications.