| Nominativ | fideicommissarium, fideicommissaria, fideicommissarius | fideicommissarii, fideicommissariae, fideicommissaria |
| Genitiv | fideicommissariae, fideicommissarii, fideicommissarii | fideicommissariorum, fideicommissariarum, fideicommissariorum |
| Dativ | fideicommissariae, fideicommissario, fideicommissario | fideicommissariis |
| Akkusativ | fideicommissariam, fideicommissarium, fideicommissarium | fideicommissarios, fideicommissarias, fideicommissaria |
| Ablativ | fideicommissario, fideicommissaria, fideicommissario | fideicommissariis |
| Vokativ | fideicommissarium, fideicommissarie, fideicommissaria | fideicommissarii, fideicommissariae, fideicommissaria |
