NOOO, it is not a quasi-Tablet, anymore than a bicycle is a quasi-motorcycle, or a motorcycle is a quasi-car. At the core of Tablet is the concept of touch screen. I would prefer a pen-enabled touch screen, but that ship sailed with the iPad. The Air is a laptop. A great instantiation of a laptop for some, but a laptop never the less. Oh, and a tablet needs to be portable, on purpose. My desktop has a touch screen, and I can move it, but I would not classify it as a tablet
There was a genre of ultra-portable for a while, but that was difficult to nail down too. Was it a function of weight? Physical size? If you want to call the Air something, though, ultra-portale probably fits.