Airproof is a term commonly used to describe something that is impervious to air, or airtight. However, there are several other words that can be used to convey a similar meaning. For example, the term airtight can be used to suggest something that is completely sealed, or impervious to air or gas. Another synonym is hermetic, which suggests a complete seal against all external influences. Likewise, watertight or waterproof could also be used to describe something that is completely airproof, as they serve as barriers against liquids as well. Ultimately, there are several words that can be used to help convey the concept of something being airproof, each with their own subtle nuances and connotations.