PIERIDES, pī̇-ĕr′ĭ-dēz (Lat., from Gk. πιερίδες). (1) A name given the Muses from their birthplace, Pieria in Thessaly. (2) According to late mythology the nine daughters of Pierus, King of Emathia, whom he named after the nine Muses. When they were defeated by the Muses in a musical contest, they were changed into magpies.