Conceptual Development: This name dates back to the earliest Lost Tales, always with essentially the same etymology and meaning. In the earliest stories it appeared as ᴱQ. Wingilot (LT1/21), and was ᴹQ. Wingelóte in The Etymologies from the 1930s (Ety/LOT(H), WIG).
Although Tolkien was consistent on the meaning of this name and its elements, he could never quite make up his mind on its exact form. The name appeared in a wide variety of forms, from his earliest to his latest writings. The variations were:
The initial letter could be V- or W-.
The middle vowel could be i, e or a.
The final syllable be -lótë or -lot.
The first of these variation probably reflects Tolkien’s uncertainty on the development of the phoneme [w] in Quenya. The second variation indicates different possible primitive forms of wingë “foam”. The third variation is simply the ordinary variation in the short and long forms of the name, also seen in names like Valinor/Valinórë and Silmaril/Silmarillë.
Vingilot/Vingilótë was the form adopted by Christopher Tolkien for the published Silmarillion, since it replaced earlier forms (sometimes but not always) in Silmarillion revisions from the 1950s-60s (WJ/246).