| Nominativ | fideicommissum, fideicommissa, fideicommissus | fideicommissi, fideicommissa, fideicommissae |
| Genitiv | fideicommissi, fideicommissi, fideicommissae | fideicommissorum, fideicommissarum, fideicommissorum |
| Dativ | fideicommisso, fideicommisso, fideicommissae | fideicommissis |
| Akkusativ | fideicommissam, fideicommissum, fideicommissum | fideicommissos, fideicommissas, fideicommissa |
| Ablativ | fideicommissa, fideicommisso, fideicommisso | fideicommissis |
| Vokativ | fideicommisse, fideicommissum, fideicommissa | fideicommissi, fideicommissa, fideicommissae |
