Source : Webster's Revised Unabridged Dictionary (1913)

Lydian \Lyd"i*an\, a. [L. Lydius, fr. Lydia, Gr. ?.]
   Of or pertaining to Lydia, a country of Asia Minor, or to its
   inhabitants; hence, soft; effeminate; -- said especially of
   one of the ancient Greek modes or keys, the music in which
   was of a soft, pathetic, or voluptuous character.

         Softly sweet in Lydian measures, Soon he soothed his
         soul to pleasures.                       --Dryden.

   {Lydian stone}, a flint slate used by the ancients to try
      gold and silver; a touchstone. See {Basanite}.

Source : WordNet®

Lydian
     n : an Anatolian language