Haudh-en-Nirnaeth is the Elvish name for 'Hill of Tears'. It was also named Haudh-en-Ndengin, which, in Elvish, is translated as 'the 'Hill of the Slain'.
This hill great heap of all the dead bodies and weapons from the fifth of the Great Battles, Nirnaeth Arnoediad, the Battle of Unnumbered Tears. It is located in Anfauglith/Ard-Galen/'The Gasping Dust'. Grass grew there shortly after its creation, and no servant of Morgoth Bauglir ever set foot on it again.