isengard

place name. Iron-court, Iron-enclosure

ang(ren)ost

place name. Isengard

angrenost

place name. Isengard, (lit.) Iron Fortress

Sindarin name of Isengard (LotR/473), a combination of angren “iron” and ost “fortress” (SA/anga, os(t); PE17/32).

Conceptual Development: In Lord of the Rings drafts from the 1940s, this name first appeared as N. Angrobel (TI/71), variously revised to N. Angost or Angrenost (TI/420; WR/44, 72), eventually settling on the latter.

Angrenost

noun. iron fortress (Isengard)

angren (“iron”) + ost (“fortress, stronghold”)

Angrenost

Fortress of Iron

It is composed of the two elements angren "iron (adjective)" and ost "fortress".