Fan-Eltharin

Fan-Eltharin is a dialect utilized by the Wood Elves of Athel Loren, derived from the original Eltharin language.

Elves are subtle creatures at heart, and live in the details of thought and deed that lesser creatures seldom notice. They live for intrigue and find joy in a clever tongue wielded by an accomplished mind. The speech of a Wood Elf is particularly incomprehensible to an outsider. This is not because the words themselves make little sense, but because there are always at least two possible interpretations of the intended meaning. In this way, a promise of assistance can sound disturbingly like a threat, and a death sentence like an offer of clemency. In this way does the speech of the Wood Elves reflect their complicated relationship with the world. Until backed up with deeds, words are just empty prophecies that speak to possible outcome; sometimes, even the Wood Elves do not know what they intend until the moment of action.

Source

 * Warhammer Armies: Wood Elves (8th Edition) -- pg. 9