The Collaborative International Dictionary of English v.0.48:

Pierian \Pi*e"ri*an\, a. [L. Pierius, from Mount Pierus, in
   Thessaly, sacred to the Muses.]
   Of or pertaining to Pierides or Muses.
   [1913 Webster]

         Drink deep, or taste not the Pierian spring. --Pope.
   [1913 Webster]