Deco - Dioc
- Decorations, Pontifical
- Decree
- Decretals, Papal
- Dedication
- Dedication, Feast of the
- Deduction
- Deer, Abbey of
- Def.
- Defender of the Matrimonial Tie
- Definitions, Theological
- Definitor (in Canon Law)
- Definitors (in Religious Orders)
- Deger, Ernst
- Degradation
- Deharbe, Joseph
- Dei Gratia; Dei Et Apostolicae Sedis Gratia
- Dei gratia; Dei et Apostolicæ Sedis gratia
- Deicolus, Saint
- Deism
- Deity
- Delacroix, Ferdinand-Victor-Eugène
- Delaroche, Hippolyte
- Delatores
- Delaware
- Delaware Indians
- Delcus
- Delegation
- Delfau, François
- Delfino, Pietro
- Delilah
- Delille, Jacques
- Delisle, Guillaume
- Delphine, Blessed
- Delrio, Martin Anton
- Delta of the Nile, Prefecture Apostolic of the
- Deluge
- Demers, Modeste
- Demetrius
- Demetrius Augustine Gallitzin
- Demetrius, Saint
