Eltharin

Eltharin, the language of the Elves, is incredibly complex in structure and massive in vocabulary, fabled in High Elf culture as being a devolved and very simplified version of the language spoken by the ancient, Godlike beings the High Elves remember as the Old Ones. In truth, it is a simplified version of the Elves’ arcane language, Anoqeyån, which is the closest surviving mortal language to the words spoken by the Old Ones.

Dialects of Eltharin include Fan-Eltharin, and Magick.

Source

 * Warhammer Fantasy RPG 2nd ED -- Realms of Sorcery -- pg. 49