Advent: The religious season before Christmas when Christians prepare to celebrate the birth of Christ.

altar: A raised table-like structure from which a priest celebrates Mass.

annulment: A canon law decree that declares that a marriage was never a valid sacrament in the first place, usually because one or both of the partners did not enter into it with good faith and intentions.

apostles: The 12 men who accompanied and supported Jesus and were trained by him to spread Christianity.

archdiocese: A large diocese run by an archbishop.

Ash Wednesday: The first day of Lent when Catholics are anointed with ashes as a reminder of their mortality.