Catechism of the Catholic Church §2851 — excerpt
In this petition, evil is not an abstraction, but refers to a person, Satan, the Evil One, the angel who opposes God. the devil (dia-bolos) is the one who "throws himself across" God's plan and his work of salvation accomplished in Christ.
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.