A noun in notes on Words, Phrases and Passages from the Lord of the Rings from the late 1950s or early 1960s, glossed “a large foamy wave” as an element in the name S. Asfaloth = “Sunlit Foam” (PE17/18). It seems to be a combination of the root √PHAL with the augmentative suffix S. -oth. Tolkien was uncertain of this etymology for Asfaloth’s name, since (in that moment) he thought sunlight words came from a root √GAS, but later he changed that to √AS and as such I think both faloth and this definition of Asfaloth are salvageable for purposes of Neo-Sindarin.