Places in Middle-earth
Region: Beleriand & North
Meaning: dark fang
[They] led [Eöl] forth to the Caragdûr, a precipice of black rock upon the north side of the hill of Gondolin, there to cast him down from the sheer walls of the city.
The Silmarillion, Quenta Silmarillion, Ch 16, Of Maeglin
carak- This root is seen in Quenya carca 'fang', of which the Sindarin form carch occurs in Carcharoth, and also in Carchost ('Fang Fort', one of the Towers of the Teeth at the entrance to Mordor). Cf. Caragdûr, Carach Angren ('Iron Jaws', the rampart and dike guarding the entrance to Udûn in Mordor), and Helcaraxë....
dûr 'dark' in Barad-dûr, Caragdûr, Dol Guldur; also in Durthang (a castle in Mordor).
The Silmarillion, Appendix: Elements in Quenya and Sindarin Names
Contributors: Elena Tiriel 10Dec08