The mountain on which Minas Tirith was built (LotR/751), translated “Towering Blue-head” in Tolkien’s “Unfinished Index” of The Lord of the Rings (RC/439). It is a combination of a shortened or root form of minas “tower” with dol(l) “head” and luin “blue” (SA/minas, dol, luin).
Conceptual Development: In Lord of the Rings drafts from the 1940s, this name first appeared as N. Tor-dilluin, perhaps beginning with N. taur “high” (as suggested by Roman Rausch, EE/3.6), but it was soon revised to N. Mindolluin (WR/80).
mindon (“isolated hill”) + luin (#Dor. “pale, #blue”)