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.
Qenya
ilma
proper name. Starlight
vista
place name. Air
Beware, older languages below! The languages below were invented during Tolkien's earlier period and should be used with caution. Remember to never, ever mix words from different languages!
This name first appeared in Silmarillion drafts from the early 1930s as ᴹQ. Silma >> Ilma >> Ilmen as a name for the “Place of Light”, home of the stars (SM/240-1). It reappeared in the mid-30s as a word for “Starlight” (LR/205), and also appeared in The Etymologies as a derivative of ᴹ√GIL, alongside (and perhaps an element of) Ilmen “region above air where stars are” (Ety/GIL).