| Sg | Pl | |
| Nom | gæfumunr | gæfumunar (rule) |
| Acc | gæfumun (rule) | gæfumuna (rule) |
| Dat | gæfumuni (rule) | gæfumunum (rule) |
| Gen | gæfumuns (rule) | gæfumuna (rule) |
| Sg | Pl | |
| Nom | gæfumunrinn (rule) | gæfumunarnir (rule) |
| Acc | gæfumuninn (rule) | gæfumunana (rule) |
| Dat | gæfumuninum (rule) | gæfumununum (rule) |
| Gen | gæfumunsins (rule) | gæfumunanna (rule) |