Christopher Tolkien has noted that Ilmen is related to such words as Ilmarë and Ilmarin.
Quenya
ilwen
feminine name. Ilwen
ilmen
Ilmen
Yón
region, any (fairly extensive) region between obstacles such as rivers or mountains
yón (2), variant of yondë, q.v. Defined as "a region, any (fairly extensive) region _between obstacles such as rivers or mountains" (PE17:43)_
ména
region
ména noun "region" (MEN). Not to be confused with the present/continuative tense of #men- "go".
yón
noun. region
A possible wife of Q. Ingwë in some 1959 notes (NM/128).