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