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