Catechism of the Catholic Church §2590 — excerpt
"Prayer is the raising of one's mind and heart to God or the requesting of good things from God" (St. John Damascene, Defide orth. 3, 24: PG 94, 1089C).
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.