A noun in The Etymologies of the 1930s for “air as substance” derived from the root ᴹ√WIS “air” (Ety/WIS). Elsewhere ᴹQ. Vista was a name for the region of (Lower) Air as the home of the birds (SM/236), but since that term seems to have become Q. vilya, I would use vista in its sense “air as substance” (the thing you breath) from The Etymologies.
Qenya
vista
place name. Air
vista
noun. air as substance
Name for the region of Air in Silmarillion notes from the 1930s (SM/236). It is simply vista “air as substance” used as a name.