Catechism of the Catholic Church §695 — excerpt
Anointing. the symbolism of anointing with oil also signifies the Holy Spirit, to the point of becoming a synonym for the Holy Spirit. In Christian initiation, anointing is the sacramental sign of Confirmation, called "chrismation" in the Churches of the East.
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.