dûr (“dark”) + thang (“compulsion, oppression”)
Sindarin
durthang
place name. Dark Oppression
Elements
Word Gloss dûr “dark (with evil implications), gloomy, hellish” thang “oppression, pressure, oppression, pressure; [N.] compulsion, duress, need; [G.] crowd, crush, herd”
Durthang
noun. dark duress, oppression
An orc-fortress in Mordor (LotR/928), translated “Dark Press or Oppression” (RC/610). This name is a compound of dûr “dark” and thang “oppression” (SA/dûr, thang).
Conceptual Development: This name was already N. Durthang when it first appeared in Lord of the Rings drafts from the 1940s (SD/33).