PIERIDES is the patronymic of the nine daughters of King Pieros of Emathia. They challenged the Muses to a contest of song, which they lost, and the Muses, in revenge, changed the presumptuous maidens into magpies (Met V.294-678; OM V.1763-1832). The Muses themselves are also called Pierides because their most ancient seat of worship was in Pieria. They were said to be the daughters of Jupiter and Mnemosyne, but their father was also said to be Pieros of Macedonia. Pierides is then either their byname of location or their patronymic.

The Man of Law says that on no account does he want to be compared with the Muses called Pierides and gives Metamorphoses as his source, MLI 90-95. The word, however, does not occur in Metamorphoses; the daughters of King Pieros are called by their byname of location, Emathides (Met V.669). Virgil uses Pierides throughout his Eclogae, and it is possible that Chaucer may have come across the word there. The narrator praises Venus, Cupid, and the Nine Sisters because through them he has told the story of Troilus's service, Tr III.1807-1920.

Pierides appears in final rhyming position, MLI 92.