One of the beacon hills of Gondor (LotR/747), translated “Fire-hilltop” (UT/319, note #51), a combination of naur “fire” and dol(l) “head, hill” (SA/dol).
Conceptual Development: When it first appeared Lord of the Rings drafts from the 1940s, this name was already N. Nardol (WR/233).
naur (“fire”) + (n-)dôl (“head”) #The first element naur usually comes out as nor in compounds; the same vowel change is seen in Iarwain < iaur + wain.