The Collaborative International Dictionary of English v.0.48:

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.
   [1913 Webster]

         Softly sweet in Lydian measures,
         Soon he soothed his soul to pleasures.   --Dryden.
   [1913 Webster]

   Lydian stone, a flint slate used by the ancients to try
      gold and silver; a touchstone. See Basanite.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Lydian
    n 1: an Anatolian language