Catechism of the Catholic Church §883 — excerpt
"The college or body of bishops has no authority unless united with the Roman Pontiff, Peter's successor, as its head." As such, this college has "supreme and full authority over the universal Church; but this power cannot be exercised without the agreement of the Roman Pontiff."
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.
Also cites: LG 22 · CIC, can 336