Catechism of the Catholic Church §2111 — excerpt
Superstition is the deviation of religious feeling and of the practices this feeling imposes. , when one attributes an importance in some way magical to certain practices otherwise lawful or necessary.
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.