Aircraft, which is both singular and plural, is or are any vehicle or vehicles that is or are capable of flying through the air, with or without the greatest of ease.
Just as an aside, I wonder if there are any crafts that are done exclusively with air? If so, wouldn’t they be aircraft was well?
Hmmm. Craft made exclusively of air. That sounds like something I could do. Who would know if I made a total mess of it?