Dwemeris

 is the language spoken by the Dwemer. While it has its roots in Aldmeris, the language has diverged significantly that the two are mutually unintelligible. It is considered one of the hardest languages to learn according to non-Dwemer and thus is very rarely spoken by members of other races. However, due to the vast expanse of Dwemer colonies, the language is frequently spoken in almost every province of Tamriel.

Source

 * Entirely based on Hrafnir's languages on the Imperial Library.