An unpleasant tongue
devised by the second for all
and found in the inner whirl of one
Black Speech
The Black Speech was created by Sauron during the Dark Years to be the sole language of all the servants of Mordor, replacing the many different varieties of Orkish and other languages used by his servants. (Source: The silmarillion)
(Thanks to Stephan ? for confirmation)
Tolkien Gateway: Black Speech