What is the name of the lake near the East Gate of Moria?

The lake near Moria’s East Gate is Mirrormere.

Mirrormere is the English name for the dark, still lake in Dimrill Dale, just outside the East Gate of Khazad-dûm. Its Dwarvish name is Kheled-zâram, usually understood as “glass-lake” or “glass-pool,” while the Sindarin name is Nen Cenedril, meaning “Lake Looking-glass.”

According to Dwarven tradition, Durin the Deathless discovered the lake after awakening at Mount Gundabad. Looking into its water, he saw a crown of stars reflected above his head. He took the vision as a favourable sign and founded Khazad-dûm beneath the surrounding mountains. Durin’s Stone later marked the site.

After escaping Moria, the Fellowship passed beside Mirrormere. Gimli stopped to look into the water, and Frodo and Sam joined him; they saw stars reflected in its depths even though they could not see their own faces. Mirrormere is a lake, not a settlement: Long Lake lies near Erebor, Lake-town is built on it, and Nen Hithoel is the river-lake near Amon Hen.